/* ---------------------------------- tokens --------------------------------- */

:root {
  color-scheme: light;

  /* brand: terracotta accent — every link, hover, and primary fill. The whole
     earth family sits at luminance 0.16-0.19 so it reads at the same weight as
     the green/coral status colors instead of as a much darker brown. */
  --brand: #b84e30;
  --brand-strong: #a8442a;
  --brand-soft: #eee8dc;
  --brand-ring: rgba(184, 78, 48, 0.18);
  --clay: #96704a;
  --clay-soft: #ebe4d6;

  /* stage accents: earth-tone family shared by section pages and cards */
  --stage-round1: #d63200;
  --stage-round2: #ad5c00;
  --stage-camp: #6d7500;
  --stage-advanced: #008216;

  /* brand glow (flat fills only — this design uses no gradients) */
  --shadow-brand: 0 10px 24px -10px rgba(184, 78, 48, 0.5);
  --shadow-brand-lg: 0 16px 34px -10px rgba(184, 78, 48, 0.62);

  /* status */
  --green: #059669;
  --green-soft: #ecfdf5;
  --amber: #b45309;
  --amber-soft: #fffbeb;
  --coral: #e11d48;
  --coral-soft: #fff1f2;
  --ochre: #a06a10;
  --ochre-soft: #f0e6d2;
  --gold: #f59e0b;

  /* neutrals: warm cream family (page background is the ABST cream #f5f0e8) */
  --ink: #111111;
  --ink-2: #2e2e2e;
  --muted: #5c5c5c;
  --muted-2: #8a8a8a;
  --line: #d8d8dd;
  --line-soft: #eeeef1;
  --paper: #ffffff;
  --panel: #fcfcfd;
  --surface-2: #f9f9fb;
  /* shapes with no border that must stay visible on near-white */
  --fill-shape: #e8e8ee;

  /* legacy aliases (kept for old rules) */
  --teal: var(--brand);
  --teal-dark: var(--brand-strong);

  /* effects */
  --shadow-sm: 0 1px 2px rgba(24, 24, 27, 0.06);
  --shadow-md: 0 1px 2px rgba(24, 24, 27, 0.04), 0 12px 28px -12px rgba(24, 24, 27, 0.14);
  --shadow-lg: 0 24px 60px -18px rgba(24, 24, 27, 0.25);
  --shadow: var(--shadow-lg);
  --radius-sm: 8px;
  --radius: 10px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --max: 1220px;

  /* layout rhythm */
  --header-h: 64px;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --page-gutter: 2rem;

  --font-body: "Outfit", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-display: "Outfit", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  /* The module reader follows usaco.guide's type scale, which is set in Inter
     rather than the Outfit used by the surrounding site chrome. */
  --font-reader: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --reader-ink: #374151; /* gray-700 — body copy and section headings */
  --reader-ink-strong: #111827; /* gray-900 — page title */
  --reader-ink-soft: #4b5563; /* gray-600 — blockquotes */
  --reader-link: #2563eb; /* blue-600 */
  --reader-rule: #d1d5db; /* gray-300 */
  --reader-code-bg: #e5e7eb; /* gray-200 */
  --ease: cubic-bezier(0.2, 0.7, 0.3, 1);

  /* motion scale */
  --t-fast: 140ms;
  --t-mid: 180ms;
  --t-slow: 280ms;
}

/* ---------------------------------- base ----------------------------------- */

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 24px);
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--font-body);
  line-height: 1.55;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
.brand strong {
  font-family: var(--font-display);
  letter-spacing: -0.015em;
}

::selection {
  background: var(--brand);
  color: white;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
  }

  html {
    scroll-behavior: auto;
  }
}

body[data-page="section"] {
  --division-accent: var(--stage-round1);
}

body[data-section="round2"] {
  --division-accent: var(--stage-round2);
}

body[data-section="camp"] {
  --division-accent: var(--stage-camp);
}

body[data-section="advanced"] {
  --division-accent: var(--stage-advanced);
}

img,
svg {
  display: block;
}

a {
  color: inherit;
}

button,
input,
select,
textarea {
  font: inherit;
}

:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 2px;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -3.5rem;
  z-index: 40;
  background: var(--ink);
  color: var(--paper);
  padding: 0.6rem 0.95rem;
  border-radius: 999px;
  font-weight: 700;
  text-decoration: none;
  transition: top var(--t-mid) var(--ease);
}

.skip-link:focus {
  top: 1rem;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* --------------------------------- header ---------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--paper) 82%, transparent);
  border-bottom: 1px solid var(--line-soft);
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(16px) saturate(1.4);
  -webkit-backdrop-filter: blur(16px) saturate(1.4);
}

.nav-shell {
  width: min(100% - var(--page-gutter), var(--max));
  min-height: var(--header-h);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 1.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  text-decoration: none;
}

.brand-mark {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  box-shadow: var(--shadow-brand);
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-size: 1.02rem;
}

.brand small {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 600;
  margin-top: -0.05rem;
}

.nav-links {
  display: flex;
  align-items: center;
  flex: 1;
  gap: var(--space-1);
}

.nav-links a,
.nav-menu summary,
.nav-login-button {
  display: inline-flex;
  align-items: center;
  gap: 0.42rem;
  text-decoration: none;
  color: var(--muted);
  font-weight: 600;
  font-size: 0.9rem;
  line-height: 1;
  padding: 0.6rem 0.85rem;
  border-radius: 999px;
  transition: color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.nav-links a:hover,
.nav-links a:focus-visible,
.nav-menu summary:hover,
.nav-menu summary:focus-visible,
.nav-login-button:hover,
.nav-login-button:focus-visible {
  color: var(--ink);
  background: var(--surface-2);
  outline: none;
}

.nav-links a.active,
.nav-menu.active summary,
.nav-menu[open] summary {
  color: var(--brand-strong);
  background: var(--brand-soft);
}

.nav-auth {
  display: inline-flex;
  align-items: center;
}

.nav-divider {
  width: 1px;
  height: 1.6rem;
  margin-left: auto;
  background: var(--line);
}

.nav-search svg {
  width: 1rem;
  height: 1rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.nav-login-button {
  border: 0;
  background: transparent;
  cursor: pointer;
  font-family: inherit;
}

.nav-user {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  max-width: 18rem;
  color: var(--ink-2);
  font-size: 0.88rem;
  font-weight: 700;
}

.nav-user span {
  max-width: 10rem;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.nav-user button {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  color: var(--brand-strong);
  cursor: pointer;
  font-size: 0.8rem;
  font-weight: 800;
  padding: 0.48rem 0.72rem;
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.nav-user button:hover,
.nav-user button:focus-visible {
  border-color: var(--brand);
  background: var(--brand-soft);
  outline: none;
}

.nav-menu {
  position: relative;
  border: 0;
  border-radius: 0;
  background: transparent;
  padding: 0;
}

.nav-menu summary {
  list-style: none;
  cursor: pointer;
}

.nav-menu summary::-webkit-details-marker {
  display: none;
}

.nav-menu summary::after {
  content: "";
  display: inline-block;
  width: 0.4rem;
  height: 0.4rem;
  margin-left: 0.45rem;
  border-right: 1.8px solid currentColor;
  border-bottom: 1.8px solid currentColor;
  transform: translateY(-0.15rem) rotate(45deg);
  transition: transform var(--t-mid) var(--ease);
}

.nav-menu[open] summary::after {
  transform: translateY(0.05rem) rotate(225deg);
}

.nav-menu-panel {
  position: absolute;
  right: 0;
  top: calc(100% + 0.55rem);
  z-index: 30;
  min-width: 232px;
  display: grid;
  gap: var(--space-1);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow-md);
  padding: var(--space-2);
  transform-origin: top right;
}

.nav-menu[open] .nav-menu-panel {
  animation: dropdown-in var(--t-mid) var(--ease);
}

@keyframes dropdown-in {
  from {
    opacity: 0;
    transform: translateY(-6px) scale(0.98);
  }

  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.nav-menu-panel a {
  display: block;
  color: var(--ink-2);
  font-size: 0.9rem;
  padding: 0.55rem 0.7rem;
  border-radius: var(--radius-sm);
  transition: color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.nav-menu-panel a:hover,
.nav-menu-panel a:focus-visible {
  color: var(--brand-strong);
  background: var(--brand-soft);
  outline: none;
}

.nav-menu-panel a.active {
  color: var(--brand-strong);
  font-weight: 700;
}

.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--ink);
  border-radius: var(--radius);
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.nav-toggle svg {
  width: 22px;
  height: 22px;
}

.nav-toggle path,
.button path,
.search-field path,
.search-field circle {
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* ---------------------------------- hero ----------------------------------- */

.hero {
  position: relative;
  min-height: min(640px, calc(100svh - 132px));
  isolation: isolate;
  overflow: hidden;
}

.hero-media,
.hero-overlay {
  position: absolute;
  inset: 0;
}

.hero-media {
  background: var(--paper);
}

.hero-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.hero-overlay {
  display: flex;
  align-items: center;
}

.hero-content {
  width: min(100% - var(--page-gutter), var(--max));
  margin: 0 auto;
  color: var(--ink);
  padding: 4.8rem 0 5.8rem;
}

.eyebrow {
  margin: 0 0 0.75rem;
  color: var(--brand);
  font-size: 0.76rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.14em;
}

.hero .eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--brand);
  background: var(--brand-soft);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.4rem 0.85rem;
}

.hero h1 {
  max-width: 780px;
  margin: 0;
  font-size: clamp(2.6rem, 6vw, 4.6rem);
  line-height: 1.02;
  letter-spacing: -0.03em;
}

.hero-copy {
  max-width: 660px;
  color: var(--muted);
  font-size: clamp(1.02rem, 2vw, 1.22rem);
  line-height: 1.6;
  margin: 1.35rem 0 0;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2.2rem;
}

/* --------------------------------- buttons --------------------------------- */

.button {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.55rem;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 700;
  padding: 0.76rem 1.35rem;
  transition: transform var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease), background var(--t-mid) var(--ease);
}

.button svg {
  width: 18px;
  height: 18px;
}

.button-primary {
  background: var(--brand);
  color: white;
  box-shadow: var(--shadow-brand);
}

.button-secondary {
  color: white;
  border: 1px solid rgba(255, 255, 255, 0.35);
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(8px);
}

.button-secondary.dark-text {
  color: var(--ink);
  border-color: var(--line);
  background: var(--panel);
}

.button:hover,
.button:focus-visible {
  transform: translateY(-2px);
  outline: none;
}

.button-primary:hover,
.button-primary:focus-visible {
  box-shadow: var(--shadow-brand-lg);
}

.button-secondary:hover,
.button-secondary:focus-visible {
  background: rgba(255, 255, 255, 0.18);
}

/* ------------------------------ scroll reveal ------------------------------ */

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 640ms var(--ease), transform 640ms var(--ease);
  transition-delay: var(--reveal-delay, 0ms);
}

.reveal.in {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
  }
}

/* -------------------------------- page shells ------------------------------ */

.page-hero,
.page-shell {
  width: min(100% - var(--page-gutter), var(--max));
  margin-left: auto;
  margin-right: auto;
}

.page-hero {
  padding: clamp(1.6rem, 4vw, 3.2rem) 0 clamp(1.2rem, 3vw, 2.1rem);
  border-bottom: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 1.5rem;
}

.page-hero.compact {
  padding-top: 1.5rem;
}

.page-hero h1 {
  max-width: 860px;
  margin: 0;
  color: var(--brand);
  font-size: clamp(2rem, 4.6vw, 3.6rem);
  line-height: 1.04;
  letter-spacing: -0.025em;
}

.page-hero p:not(.eyebrow) {
  max-width: 720px;
  color: var(--muted);
  margin: 0.9rem 0 0;
  font-size: 1.05rem;
  line-height: 1.6;
}

.page-shell {
  margin-top: 2rem;
  margin-bottom: 4.5rem;
}

/* ---------------------------------- auth ----------------------------------- */

body.auth-modal-open {
  overflow: hidden;
}

.auth-shell {
  display: grid;
  justify-items: center;
}

.auth-panel {
  display: grid;
  gap: 1.25rem;
  width: min(100%, 640px);
  padding: clamp(1.4rem, 4vw, 2rem);
  border: 1px solid color-mix(in srgb, var(--brand) 26%, var(--line));
  border-radius: var(--radius-lg);
  background:
    linear-gradient(90deg, rgba(184, 78, 48, 0.08), transparent 36%),
    var(--panel);
  box-shadow: var(--shadow-md);
}

.auth-panel h2 {
  margin: 0;
  color: var(--brand);
  font-size: clamp(1.55rem, 3vw, 2.25rem);
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.auth-panel p:not(.eyebrow) {
  margin: 0.75rem 0 0;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.65;
}

.auth-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.auth-status {
  min-height: 1.4rem;
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 700;
}

.auth-modal {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: grid;
  place-items: center;
  padding: 1rem;
}

.auth-modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(17, 24, 39, 0.46);
  backdrop-filter: blur(3px);
}

.auth-modal-card {
  position: relative;
  display: grid;
  gap: 1.4rem;
  width: min(100%, 660px);
  padding: clamp(1.6rem, 4vw, 2.2rem);
  border: 1px solid color-mix(in srgb, var(--brand) 24%, var(--line));
  border-radius: var(--radius-lg);
  background:
    linear-gradient(90deg, rgba(184, 78, 48, 0.08), transparent 42%),
    var(--panel);
  box-shadow: 0 26px 70px rgba(17, 24, 39, 0.28);
}

.auth-modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  display: inline-grid;
  place-items: center;
  width: 2.4rem;
  height: 2.4rem;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.auth-modal-close:hover,
.auth-modal-close:focus-visible {
  color: var(--ink);
  background: var(--surface-2);
  outline: none;
}

.auth-modal-close svg {
  width: 1.65rem;
  height: 1.65rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
}

.auth-modal-copy {
  padding-right: 2.6rem;
}

.auth-modal-copy h2 {
  margin: 0;
  color: var(--brand);
  font-size: clamp(1.7rem, 4vw, 2.35rem);
  line-height: 1.08;
}

.auth-modal-copy p,
.auth-modal-signed-in p {
  max-width: 56ch;
  margin: 0.75rem 0 0;
  color: var(--muted);
  font-size: 1.08rem;
  line-height: 1.55;
}

.auth-modal-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}

.auth-provider-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.85rem;
  min-height: 3.2rem;
  min-width: min(100%, 18rem);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink-2);
  cursor: pointer;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 800;
  box-shadow: var(--shadow-sm);
  transition:
    border-color var(--t-fast) var(--ease),
    box-shadow var(--t-fast) var(--ease),
    transform var(--t-fast) var(--ease),
    color var(--t-fast) var(--ease);
}

.auth-provider-button:hover,
.auth-provider-button:focus-visible {
  color: var(--brand-strong);
  border-color: color-mix(in srgb, var(--brand) 50%, var(--line));
  box-shadow: var(--shadow-md);
  outline: none;
  transform: translateY(-1px);
}

.auth-provider-button svg {
  width: 1.45rem;
  height: 1.45rem;
  fill: currentColor;
}

.auth-modal-signed-in {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.9rem;
}

/* -------------------------------- dashboard -------------------------------- */

body[data-page="dashboard"] {
  background: var(--paper);
}

.dashboard-main {
  min-height: calc(100svh - var(--header-h));
}

.dashboard-shell {
  width: min(100% - var(--page-gutter), 1060px);
  margin: 0 auto;
  padding: 1.2rem 0 4rem;
}

.dashboard-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: 1.2rem 1.3rem;
}

.dashboard-card h2 {
  margin: 0 0 0.85rem;
  font-size: 1.02rem;
  letter-spacing: -0.01em;
}

.dash-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 1.5rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  color: var(--ink);
  padding: 1.6rem 1.75rem;
  box-shadow: var(--shadow-sm);
}

.dash-hero h1 {
  margin: 0;
  color: var(--brand);
  font-size: 1.55rem;
  letter-spacing: -0.02em;
}

.dash-hero p {
  margin: 0.35rem 0 0;
  color: var(--muted);
  font-weight: 600;
}


.kpi-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1.1rem;
}

.kpi-tile {
  display: grid;
  gap: 0.5rem;
  align-content: start;
}

.kpi-tile span {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.07em;
}

.kpi-tile strong {
  font-family: var(--font-display);
  font-size: 1.9rem;
  line-height: 1;
}

.kpi-tile strong small {
  color: var(--muted-2);
  font-size: 0.95rem;
  font-weight: 600;
  margin-left: 0.3rem;
}

.dash-columns {
  display: grid;
  grid-template-columns: minmax(0, 2fr) minmax(260px, 1fr);
  gap: 1rem;
  margin-top: 1rem;
}

.dashboard-card h2 {
  margin: 0;
  color: var(--ink);
  letter-spacing: -0.015em;
}

.dashboard-continue {
  min-height: 48px;
  /* Light outline button: a pale fill alone is invisible on the panel card
     (1.2:1), so the terracotta border is what makes it read as a button. */
  border: 1px solid var(--brand);
  border-radius: 999px;
  background: var(--brand-soft);
  color: var(--brand-strong);
  padding: 0.7rem 1.5rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: none;
  transition: transform var(--t-mid) var(--ease), background var(--t-mid) var(--ease);
}

.dashboard-continue:hover,
.dashboard-continue:focus-visible {
  transform: translateY(-2px);
  background: var(--surface-2);
}

.activity-card {
  min-width: 0;
  margin-top: 1rem;
}

.activity-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.activity-legend {
  display: flex;
  align-items: center;
  gap: 4px;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 600;
}

.activity-legend span {
  margin: 0 0.25rem;
}

.activity-scroll {
  margin-top: 1rem;
  overflow-x: auto;
  padding-bottom: 0.25rem;
}

.activity-months {
  display: flex;
  justify-content: space-between;
  width: 958px;
  color: var(--muted-2);
  font-weight: 700;
  font-size: 0.8rem;
  padding: 0 0.2rem;
  margin: 0 auto;
}

.activity-heatmap {
  width: 958px;
  margin: 0.4rem auto 0;
  display: grid;
  grid-template-rows: repeat(7, 15px);
  grid-auto-flow: column;
  grid-auto-columns: 15px;
  gap: 3.5px;
}

.activity-square {
  display: inline-block;
  width: 15px;
  height: 15px;
  border-radius: 2px;
  background: var(--fill-shape);
}

.activity-square.level-1 {
  background: #9be9a8;
}

.activity-square.level-2 {
  background: #40c463;
}

.activity-square.level-3 {
  background: #30a14e;
}

.activity-square.level-4 {
  background: #216e39;
}


/* ----------------------------- section (division) -------------------------- */

.division-hero {
  background: var(--paper);
  border-bottom: 1px solid var(--line);
}

.division-hero-inner {
  width: min(100% - var(--page-gutter), 940px);
  margin: 0 auto;
  padding: clamp(2rem, 4.5vw, 3.2rem) 0 clamp(1.8rem, 4vw, 2.6rem);
}

.stage-switch {
  display: inline-flex;
  gap: 2px;
  padding: 3px;
  margin-bottom: 1.5rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  box-shadow: var(--shadow-sm);
}

.stage-switch a {
  padding: 0.42rem 0.95rem;
  border-radius: 999px;
  text-decoration: none;
  color: var(--muted);
  font-weight: 700;
  font-size: 0.85rem;
  line-height: 1;
  transition: color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.stage-switch a:hover,
.stage-switch a:focus-visible {
  color: var(--ink);
  background: var(--surface-2);
  outline: none;
}

.stage-switch a.active {
  color: white;
  background: var(--division-accent);
}

.division-hero h1 {
  margin: 0;
  color: var(--brand);
  font-size: clamp(2.3rem, 5vw, 3.5rem);
  line-height: 1.02;
  letter-spacing: -0.03em;
}

.division-hero p {
  max-width: 680px;
  margin: 0.9rem 0 0;
  color: var(--ink-2);
  font-size: 1.04rem;
  line-height: 1.6;
}

.division-note {
  color: var(--muted);
  font-size: 0.9rem;
}

.stage-progress {
  margin-top: 1.7rem;
}

.stage-progress-card {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(1.2rem, 3vw, 2.6rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  box-shadow: var(--shadow-sm);
  padding: 1.2rem 1.4rem;
}

.stage-meter-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.75rem;
}

.stage-meter-head span {
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.stage-meter-head b {
  color: var(--ink);
  font-size: 0.9rem;
  white-space: nowrap;
}

.stage-meter .meter-track {
  margin-top: 0.6rem;
}

.stage-meter .meter-fill {
  background: var(--division-accent);
}

.stage-meter-detail {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
  margin-top: 0.55rem;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 600;
}

.stage-dot::before {
  content: "";
  display: inline-block;
  width: 7px;
  height: 7px;
  border-radius: 999px;
  margin-right: 0.35rem;
  background: var(--muted-2);
}

.stage-dot.in-progress::before {
  background: var(--amber);
}

.stage-dot.skipped::before {
  background: var(--ochre);
}

.division-roadmap-wrap {
  background: var(--paper);
}

.division-roadmap {
  width: min(100% - var(--page-gutter), 900px);
  margin: 0 auto;
  padding: clamp(1.8rem, 4vw, 2.8rem) 0 4.5rem;
  display: grid;
  gap: 1.25rem;
}

.chapter-card {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.chapter-card-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  padding: 1.1rem 1.3rem;
  border-bottom: 1px solid var(--line-soft);
  background: var(--surface-2);
}

.chapter-kicker {
  color: var(--division-accent);
  font-size: 0.72rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.chapter-card-title h2 {
  margin: 0.2rem 0 0;
  font-size: 1.25rem;
  letter-spacing: -0.015em;
}

.chapter-card-title p {
  margin: 0.4rem 0 0;
  max-width: 560px;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.55;
}

.chapter-card-head .chapter-meter {
  flex: none;
  margin-top: 0.35rem;
}

/* The topic rows sit white against the tinted chapter header, so the header
   reads as the card's title band rather than blending into the list. */
.chapter-topics {
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--paper);
}

.chapter-topics li + li {
  border-top: 1px solid var(--line-soft);
}

.topic-row {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr) auto;
  gap: 0.9rem;
  align-items: start;
  padding: 0.9rem 1.3rem;
  color: var(--ink);
  text-decoration: none;
  transition: background var(--t-fast) var(--ease);
}

.topic-row:hover,
.topic-row:focus-visible {
  background: var(--surface-2);
  outline: none;
}

.topic-row:hover .topic-copy strong,
.topic-row:focus-visible .topic-copy strong {
  color: var(--division-accent);
}

.topic-index {
  width: 30px;
  height: 30px;
  margin-top: 0.1rem;
  border-radius: 999px;
  display: grid;
  place-items: center;
  /* --surface-2 would all but vanish on the now-white row */
  background: var(--fill-shape);
  color: var(--muted);
  font-weight: 800;
  font-size: 0.8rem;
}

.topic-index.done {
  background: var(--green-soft);
  color: var(--green);
}

.topic-row .mini-status {
  margin-top: 0.35rem;
}

.topic-copy {
  display: grid;
  gap: 0.18rem;
}

.topic-copy strong {
  font-size: 1.05rem;
  line-height: 1.3;
  color: var(--ink-2);
  transition: color var(--t-fast) var(--ease);
}

.topic-copy small,
.topic-copy em {
  color: var(--muted-2);
  font-size: 0.86rem;
  font-style: normal;
  line-height: 1.4;
}

/* ------------------------------- card grids -------------------------------- */

.route-grid,
.section-link-grid {
  display: grid;
  gap: 1rem;
}

.route-grid {
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
}

.route-card {
  position: relative;
  display: grid;
  align-content: start;
  min-height: 170px;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  color: var(--ink);
  text-decoration: none;
  padding: 1.15rem;
  overflow: hidden;
  transition: transform var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease), border-color var(--t-mid) var(--ease);
}

.route-card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 4px;
  background: var(--brand);
}

.route-card:nth-child(2)::before {
  background: var(--stage-advanced);
}

.route-card:nth-child(3)::before {
  background: var(--stage-round2);
}

.route-card:nth-child(4)::before {
  background: var(--stage-camp);
}

.route-card:nth-child(5)::before {
  background: var(--brand-strong);
}

.route-card span {
  color: var(--muted);
  font-size: 0.75rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.route-card strong {
  display: block;
  margin-top: 0.45rem;
  font-family: var(--font-display);
  font-size: 1.15rem;
  letter-spacing: -0.01em;
}

.route-card small {
  color: var(--muted);
  margin-top: 0.5rem;
  font-size: 0.9rem;
  line-height: 1.5;
}

.route-card:hover,
.route-card:focus-visible,
.section-link-grid a:hover,
.section-link-grid a:focus-visible {
  border-color: var(--brand);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  outline: none;
}

.section-link-grid {
  grid-template-columns: repeat(4, 1fr);
  margin-bottom: 1rem;
}

.section-link-grid a {
  min-height: 52px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface-2);
  color: var(--ink);
  font-weight: 700;
  text-decoration: none;
  transition: transform var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease), border-color var(--t-mid) var(--ease);
}

/* ------------------------------- shell layout ------------------------------ */

.guide-shell {
  width: min(100% - var(--page-gutter), var(--max));
  margin: 2rem auto 4rem;
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 1.1rem;
  align-items: start;
}

.side-panel {
  position: sticky;
  top: calc(var(--header-h) + 24px);
  display: grid;
  gap: 1.1rem;
}

.panel,
.side-section,
.progress-box {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.panel {
  padding: clamp(1.2rem, 2vw, 1.75rem);
  min-width: 0;
}

.progress-box,
.side-section {
  padding: 1.15rem;
}

.progress-box h2,
.section-heading h2,
.side-section h3,
.module-card h3,
.timeline h3,
.resource-card h3 {
  margin: 0;
  letter-spacing: -0.015em;
}

.progress-box h2 {
  font-size: 1.2rem;
}

.progress-meter {
  margin-top: 1.1rem;
}

.progress-meter span {
  display: block;
  color: var(--muted);
  font-size: 0.9rem;
  margin-bottom: 0.5rem;
}

.meter-track {
  height: 8px;
  background: var(--fill-shape);
  border-radius: 999px;
  overflow: hidden;
}

.meter-fill {
  width: 0%;
  height: 100%;
  border-radius: inherit;
  background: var(--brand);
  transition: width var(--t-slow) var(--ease);
}

.side-section {
  display: grid;
  gap: 0.72rem;
}

.side-section h3 {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.side-section a {
  color: var(--ink);
  text-decoration: none;
  font-weight: 600;
  padding: 0.4rem 0;
  border-bottom: 1px solid var(--line-soft);
  transition: color var(--t-fast) var(--ease);
}

.side-section a:hover,
.side-section a:focus-visible {
  color: var(--brand);
  outline: none;
}

/* ------------------------------ dashboard cards ---------------------------- */

.dashboard-grid,
.status-summary {
  display: grid;
  gap: 1rem;
}

.dashboard-grid {
  grid-template-columns: repeat(4, 1fr);
}

.dash-card,
.dash-wide {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  box-shadow: var(--shadow-sm);
  padding: 1.1rem;
  min-width: 0;
}

.dash-card span,
.dash-wide h3 {
  color: var(--muted);
  font-weight: 700;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.dash-card strong {
  display: block;
  font-family: var(--font-display);
  font-size: 2.1rem;
  line-height: 1;
  margin: 0.5rem 0;
}

.dash-card p,
.muted-copy {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.dash-wide {
  grid-column: span 2;
}

.dash-wide h3 {
  margin: 0 0 0.8rem;
  color: var(--ink);
}


.status-summary {
  grid-template-columns: repeat(4, 1fr);
  margin-top: 1rem;
}

.status-pill {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  padding: 0.9rem;
}

.status-pill strong,
.status-pill span {
  display: block;
}

.status-pill strong {
  font-family: var(--font-display);
  font-size: 1.3rem;
}

.status-pill span {
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 700;
}

.balance-row {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.balance-row strong {
  color: var(--ink);
}

.content-stack {
  display: grid;
  gap: 1.1rem;
  min-width: 0;
}

.content-stack > * {
  min-width: 0;
}

.section-heading {
  max-width: 760px;
  margin-bottom: 1.4rem;
}

.section-heading.compact {
  margin-bottom: 1rem;
}

.section-heading.subheading {
  margin-top: 1.6rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

.section-heading h2 {
  position: relative;
  margin: 0;
  padding-bottom: 0.6rem;
  font-size: 1.3rem;
  line-height: 1.2;
  letter-spacing: -0.015em;
}

.section-heading h2::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 42px;
  height: 3px;
  border-radius: 999px;
  background: var(--brand);
}

.section-heading p {
  margin: 0.65rem 0 0;
  color: var(--muted);
  font-size: 0.94rem;
  line-height: 1.6;
}

/* ------------------------------ tabs & filters ----------------------------- */

.tab-list,
.filter-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tab-button,
.filter-chip {
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--muted);
  border-radius: 999px;
  font-weight: 700;
  cursor: pointer;
  transition: color var(--t-fast) var(--ease), background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.tab-button {
  min-height: 42px;
  padding: 0.6rem 1.05rem;
}

.filter-chip {
  min-height: 38px;
  padding: 0.5rem 0.9rem;
  font-size: 0.9rem;
}

.tab-button:hover,
.filter-chip:hover,
.tab-button:focus-visible,
.filter-chip:focus-visible {
  color: var(--brand-strong);
  background: var(--brand-soft);
  border-color: var(--brand-ring);
  outline: none;
}

.tab-button.active,
.filter-chip.active {
  color: white;
  background: var(--ink);
  border-color: var(--ink);
}

.mini-status {
  border-radius: 999px;
  border: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.68rem;
  font-weight: 800;
  padding: 0.12rem 0.42rem;
  white-space: nowrap;
}

.mini-status.status-complete {
  color: var(--green);
  border-color: color-mix(in srgb, var(--green) 40%, transparent);
  background: var(--green-soft);
}

.mini-status.status-in-progress {
  color: var(--ochre);
  border-color: color-mix(in srgb, var(--ochre) 40%, transparent);
  background: var(--ochre-soft);
}

.mini-status.status-skipped {
  color: var(--coral);
  border-color: color-mix(in srgb, var(--coral) 40%, transparent);
  background: var(--coral-soft);
}

/* --------------------------------- toolbar --------------------------------- */

.toolbar {
  display: grid;
  gap: 0.9rem;
  margin-bottom: 1.1rem;
}

.table-filter-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(160px, 240px));
  gap: 0.75rem;
  align-items: end;
}

.search-field {
  display: flex;
  align-items: center;
  min-height: 50px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  padding: 0 1.1rem;
  gap: 0.6rem;
  transition: border-color var(--t-fast) var(--ease), box-shadow var(--t-fast) var(--ease);
}

.search-field:focus-within {
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-ring);
}

.search-field svg {
  width: 20px;
  height: 20px;
  color: var(--muted);
  flex: 0 0 auto;
}

.search-field input {
  width: 100%;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--ink);
}

.search-field input::placeholder {
  color: var(--muted-2);
}

/* ------------------------------- module cards ------------------------------ */

.module-grid,
.resource-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

.card-topline {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}


.module-card,
.resource-card {
  position: relative;
  min-height: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  padding: 1.15rem;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
  overflow: hidden;
  transition: transform var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease), border-color var(--t-mid) var(--ease);
}

.module-card:hover,
.resource-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: color-mix(in srgb, var(--brand) 35%, var(--line));
}

.module-card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 4px;
  background: var(--stage-round1);
}

.module-card[data-category="round2"]::before {
  background: var(--stage-round2);
}

.module-card[data-category="camp"]::before {
  background: var(--stage-camp);
}

.module-card[data-category="advanced"]::before {
  background: var(--stage-advanced);
}

.card-kicker,
.resource-card small {
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.module-card h3 {
  font-size: 1.08rem;
}

.module-card p,
.resource-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.55;
}

.module-list {
  margin: 0;
  padding-left: 1.1rem;
  color: var(--ink);
  font-size: 0.9rem;
}

.module-list li + li {
  margin-top: 0.28rem;
}

.module-list li::marker {
  color: var(--brand);
}

.module-prereq {
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 600;
}

.module-actions {
  margin-top: auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.7rem;
}

.complete-button {
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--ink);
  padding: 0.5rem 0.95rem;
  font-weight: 700;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease);
}

.complete-button:hover,
.complete-button:focus-visible {
  border-color: var(--brand);
  transform: translateY(-1px);
  outline: none;
}

.complete-button.done {
  background: var(--green-soft);
  border-color: color-mix(in srgb, var(--green) 40%, transparent);
  color: var(--green);
}

.complete-button.danger {
  color: white;
  background: var(--coral);
  border-color: var(--coral);
}

.button-lite,
.link-button {
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--ink);
  padding: 0.5rem 0.95rem;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease);
}

.button-lite:hover,
.link-button:hover,
.button-lite:focus-visible,
.link-button:focus-visible {
  border-color: var(--brand);
  transform: translateY(-1px);
  outline: none;
}


.status-select {
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--ink);
  padding: 0.45rem 2.1rem 0.45rem 0.9rem;
  font-weight: 600;
  max-width: 160px;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  background-color: var(--panel);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.85rem center;
  background-size: 11px;
  transition: border-color var(--t-fast) var(--ease), box-shadow var(--t-fast) var(--ease);
}

.status-select:hover {
  border-color: color-mix(in srgb, var(--brand) 40%, var(--line));
}

.status-select:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-ring);
}

.status-select.full {
  width: 100%;
  max-width: none;
  min-width: 138px;
}

/* ------------------------------- module reader ----------------------------- */

.module-reader {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 1.1rem;
}


.reader-sidebar {
  align-self: start;
  position: sticky;
  top: calc(var(--header-h) + 24px);
}

.reader-sidebar h3,
.reader-content h3,
.lesson-section h4 {
  margin: 0;
  letter-spacing: -0.01em;
}

.reader-sidebar p {
  color: var(--muted);
}

.field-label {
  display: grid;
  gap: 0.4rem;
  color: var(--muted);
  font-weight: 700;
  font-size: 0.88rem;
  margin: 0.9rem 0;
}

.field-label.compact {
  margin: 0;
}

.toc {
  display: grid;
  gap: 0.35rem;
  margin-top: 1rem;
  border-top: 1px solid var(--line);
  padding-top: 1rem;
}

.toc a {
  color: var(--brand-strong);
  text-decoration: none;
  font-weight: 600;
}

.reader-header,
.reader-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.lesson-section {
  margin-top: 1rem;
  border-top: 1px solid var(--line);
  padding-top: 1rem;
}

.lesson-section p {
  color: var(--muted);
}

.mini-problem-list {
  display: grid;
  gap: 0.55rem;
}

.mini-problem-list button {
  text-align: left;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface-2);
  padding: 0.75rem;
  color: var(--ink);
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease);
}

.mini-problem-list button:hover {
  border-color: var(--brand);
}

.mini-problem-list strong,
.mini-problem-list span {
  display: block;
}

.mini-problem-list span {
  color: var(--muted);
  font-size: 0.86rem;
}

body[data-page="module"] {
  /* Reader inherits the site's warm palette, at documentation density: 16px
     body text on a ~760px measure, the way usaco.guide sets a module. */
  --reader-zoom: 1;
  background: var(--paper);
}

.reader-main {
  min-height: calc(100svh / var(--reader-zoom, 1));
}

/* Sidebar | gutter | article | gutter. The lesson contents list lives inside
   the article now, so there is no fourth column for a separate TOC panel. */
.usaco-reader {
  width: 100%;
  min-height: calc(100svh / var(--reader-zoom, 1));
  display: grid;
  grid-template-columns: 355px minmax(2rem, 0.55fr) minmax(0, 896px) minmax(2rem, 1.45fr);
  gap: 0;
  background: #fff;
}

/* --- left sidebar ---------------------------------------------------------- */

.reader-sidenav {
  grid-column: 1;
  position: sticky;
  top: 0;
  height: calc(100svh / var(--reader-zoom, 1));
  display: flex;
  flex-direction: column;
  border-right: 1px solid var(--line-soft);
  background: var(--panel);
}

.usaco-reader.nav-collapsed {
  grid-template-columns: 0 minmax(2rem, 0.8fr) minmax(0, 896px) minmax(2rem, 1.2fr);
}

.reader-sidenav .reader-nav-scroll::-webkit-scrollbar {
  width: 8px;
}

.reader-sidenav .reader-nav-scroll::-webkit-scrollbar-thumb {
  border-radius: 999px;
  background: var(--line);
}

.usaco-reader.nav-collapsed .reader-sidenav {
  display: none;
}

.reader-nav-fab {
  position: fixed;
  left: 0.9rem;
  top: 0.9rem;
  z-index: 40;
  display: none;
  place-items: center;
  width: 38px;
  height: 38px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  color: var(--muted);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.reader-nav-fab:hover,
.reader-nav-fab:focus-visible {
  color: var(--brand);
  border-color: var(--brand-ring);
  outline: none;
}

.reader-nav-fab svg {
  width: 17px;
  height: 17px;
}

.usaco-reader.nav-collapsed .reader-nav-fab {
  display: grid;
}

.reader-nav-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  padding: 1.45rem 0.85rem 0.85rem 1.4rem;
}

.reader-logo {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  min-width: 0;
  color: var(--ink);
  text-decoration: none;
}

.reader-logo strong {
  font-family: var(--font-display);
  font-size: 1.02rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  white-space: nowrap;
}

.reader-logo-mark {
  width: 30px;
  height: 30px;
  flex: 0 0 auto;
}

.reader-nav-toggle {
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  flex: 0 0 auto;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--muted-2);
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.reader-nav-toggle:hover,
.reader-nav-toggle:focus-visible {
  background: var(--surface-2);
  color: var(--ink);
  outline: none;
}

.reader-nav-toggle svg {
  width: 15px;
  height: 15px;
}

.reader-stage {
  position: relative;
  z-index: 30;
  border: 0;
  border-radius: 0;
  background: transparent;
  padding: 0.95rem 1rem 1.15rem;
  border-bottom: 1px solid var(--line);
  text-align: center;
}

.reader-stage summary {
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.45rem 0.9rem;
  border-radius: 8px;
  color: var(--ink);
  font-family: var(--font-display);
  font-size: 1.02rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  cursor: pointer;
  user-select: none;
  transition: background var(--t-fast) var(--ease);
}

.reader-stage summary::-webkit-details-marker {
  display: none;
}

.reader-stage summary:hover {
  background: var(--surface-2);
}

.reader-stage summary::after {
  content: "";
  width: 7px;
  height: 7px;
  margin-top: -4px;
  border-right: 2px solid var(--muted-2);
  border-bottom: 2px solid var(--muted-2);
  border-radius: 0;
  transform: rotate(45deg);
  transition: transform var(--t-fast) var(--ease);
}

.reader-stage[open] summary::after {
  margin-top: 3px;
  transform: rotate(-135deg);
}

.reader-stage-menu {
  position: absolute;
  left: 50%;
  top: calc(100% - 0.4rem);
  transform: translateX(-50%);
  min-width: 168px;
  display: grid;
  gap: 2px;
  padding: 0.35rem;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--panel);
  box-shadow: var(--shadow-md);
  text-align: left;
}

.reader-stage-menu a {
  padding: 0.5rem 0.7rem;
  border-radius: 6px;
  color: var(--ink-2);
  font-size: 0.86rem;
  font-weight: 600;
  text-decoration: none;
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.reader-stage-menu a:hover,
.reader-stage-menu a:focus-visible {
  background: var(--surface-2);
  color: var(--ink);
  outline: none;
}

.reader-stage-menu a.active {
  color: var(--brand-strong);
  background: var(--brand-soft);
}

.reader-nav-scroll {
  flex: 1;
  overflow-y: auto;
}

.reader-chapter {
  border: 0;
  border-radius: 0;
  background: transparent;
  padding: 0;
  border-bottom: 1px solid var(--line);
}

.reader-chapter + .reader-chapter {
  margin-top: 0;
}

.reader-chapter.active {
  background: var(--surface-2);
}

.reader-chapter summary {
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem;
  padding: 1.05rem 1.2rem 1.05rem 0.9rem;
  color: var(--ink);
  font-size: 0.92rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  cursor: pointer;
  user-select: none;
}

.reader-chapter summary::-webkit-details-marker {
  display: none;
}

.reader-chapter summary::after {
  content: "";
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  margin-top: 2px;
  border-right: 2px solid var(--muted);
  border-bottom: 2px solid var(--muted);
  border-radius: 0;
  transform: rotate(-45deg);
  transition: transform var(--t-fast) var(--ease);
}

.reader-chapter[open] summary::after {
  margin-top: -4px;
  transform: rotate(45deg);
}

.reader-chapter ol {
  list-style: none;
  margin: 0;
  padding: 0.4rem 0 1.15rem;
}

.reader-chapter li {
  position: relative;
}

.reader-chapter li::before {
  content: "";
  position: absolute;
  left: 20px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--line);
}

.reader-chapter li:first-child::before {
  top: 50%;
}

.reader-chapter li:last-child::before {
  bottom: 50%;
}

.reader-chapter li.active::before {
  left: 19.5px;
  width: 3px;
  background: var(--brand);
}

.reader-chapter a {
  position: relative;
  display: block;
  padding: 0.8rem 1rem 0.8rem 40px;
  color: var(--muted);
  font-size: 0.88rem;
  font-weight: 400;
  line-height: 1.55;
  text-decoration: none;
  transition: color var(--t-fast) var(--ease);
}

.reader-chapter a:hover,
.reader-chapter a:focus-visible {
  color: var(--ink);
  outline: none;
}

.reader-chapter a.active {
  color: var(--brand);
  font-weight: 500;
}

.reader-nav-dot {
  position: absolute;
  left: 21px;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 9px;
  height: 9px;
  border-radius: 999px;
  background: var(--line);
}

.reader-chapter a.active .reader-nav-dot {
  width: 11px;
  height: 11px;
  background: var(--brand);
}

.reader-nav-title {
  display: block;
  min-width: 0;
}

.reader-nav-footer {
  border-top: 1px solid var(--line-soft);
}

.reader-nav-footer a {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.75rem 1rem;
  color: var(--ink-2);
  font-size: 0.88rem;
  font-weight: 600;
  text-decoration: none;
  transition: color var(--t-fast) var(--ease);
}

.reader-nav-footer a + a {
  border-top: 1px solid var(--line-soft);
}

.reader-nav-footer svg {
  width: 15px;
  height: 15px;
  color: var(--muted-2);
  flex: 0 0 auto;
}

/* --- article --------------------------------------------------------------- */

.reader-article {
  grid-column: 3;
  min-width: 0;
  padding: 2rem 2rem 5rem;
}

/* --- top bar: prev · breadcrumb · next ------------------------------------- */

.reader-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-bottom: 1.9rem;
}

.reader-step {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  border-radius: var(--radius-sm);
  padding: 0.35rem 0.7rem;
  color: var(--muted);
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.reader-step:hover,
.reader-step:focus-visible {
  background: var(--brand-soft);
  color: var(--brand-strong);
  outline: none;
}

.reader-step svg {
  width: 18px;
  height: 18px;
}

.reader-step.is-disabled {
  pointer-events: none;
}

.reader-crumbs {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  min-width: 0;
  color: var(--muted);
  font-size: 0.85rem;
  line-height: 1.4;
}

.reader-crumbs a {
  color: var(--muted);
  text-decoration: none;
  transition: color var(--t-fast) var(--ease);
}

.reader-crumbs a:hover,
.reader-crumbs a:focus-visible {
  color: var(--brand-strong);
  outline: none;
}

.reader-crumbs [aria-current="page"] {
  color: var(--ink);
  font-weight: 600;
}

.reader-crumb-sep {
  width: 18px;
  height: 18px;
  flex: none;
  margin: 0 0.15rem;
  color: var(--muted-2);
}

.reader-head {
  padding: 2.2rem 0 1.6rem;
  border-bottom: 1px solid var(--line-soft);
}

.reader-head h1 {
  margin: 0;
  color: var(--ink);
  font-size: 2.05rem;
  line-height: 1.15;
  letter-spacing: 0;
}

.reader-lede {
  margin: 0.9rem 0 0;
  color: var(--muted);
  font-size: 1.02rem;
  line-height: 1.7;
}

.reader-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin: 1.15rem 0 0;
  color: var(--muted-2);
  font-size: 0.8rem;
}

.reader-topnote {
  display: block;
  margin: 1.75rem 0 1.25rem;
  border-left: 4px solid var(--brand);
  border-radius: 0 8px 8px 0;
  background: color-mix(in srgb, var(--brand-soft) 68%, #fff);
  color: var(--muted);
  padding: 10px 14px;
  line-height: 1.6;
}

.reader-topnote strong {
  color: var(--ink);
}

.reader-topnote span {
  margin-left: 0.35rem;
}


.reader-chip {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.1rem 0.6rem;
  white-space: nowrap;
}

.reader-chip.accent {
  color: var(--brand-strong);
  background: var(--brand-soft);
  border-color: var(--brand-ring);
}

.reader-toolbar {
  display: grid;
  flex: none;
  gap: 0.35rem;
  margin-top: 0.1rem;
}

.reader-toolbar span {
  color: var(--muted-2);
  font-size: 0.66rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  line-height: 1;
  text-transform: uppercase;
}

.reader-toolbar .status-select {
  min-height: 32px;
  font-size: 0.78rem;
  padding: 0.25rem 1.9rem 0.25rem 0.75rem;
}


/* --- sections -------------------------------------------------------------- */

.reader-section {
  margin-top: 2.3rem;
  scroll-margin-top: 1.5rem;
}

.reader-notebook-cell {
  margin-top: 24px;
}

.reader-section h2 {
  margin: 0 0 0.9rem;
  color: var(--muted-2);
  font-size: 0.72rem;
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

/* A lesson section is one topic, so its label is the topic heading the reader
   actually reads — not the uppercase kicker used for "Learning Outcomes". */
.reader-section h2.reader-section-label {
  margin: 0 0 0.9rem;
  color: var(--ink);
  font-size: 2.05rem;
  font-weight: 750;
  line-height: 1.15;
  letter-spacing: 0;
  text-transform: none;
}

/* The "#" that appears on hover, the way a docs site offers a link to the
   section you are reading. It never affects the heading's layout. */
.reader-anchor {
  margin-left: 0.45rem;
  color: var(--brand);
  font-weight: 600;
  text-decoration: none;
  opacity: 0;
  transition: opacity var(--t-fast) var(--ease);
}

.reader-section h2:hover .reader-anchor,
.reader-anchor:focus-visible {
  opacity: 1;
  outline: none;
}

.reader-section p,
.reader-section li {
  color: var(--ink);
  font-size: 1rem;
  line-height: 1.7;
}

.reader-section > p,
.reader-section p {
  margin: 0 0 0.95rem;
}

.reader-section p:last-child {
  margin-bottom: 0;
}

.reader-section ul,
.reader-section ol {
  margin: 0 0 1rem;
  padding-left: 1.2rem;
}

.reader-key-list,
.reader-steps {
  display: grid;
  gap: 0.62rem;
  margin-top: 0.75rem;
}

.reader-key-list li::marker,
.reader-steps li::marker {
  color: var(--brand);
  font-weight: 700;
}

.reader-subblock {
  margin-top: 1.5rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--surface-2);
  padding: 1.2rem 1.35rem;
}

.reader-subblock h3 {
  margin: 0 0 0.5rem;
  color: var(--muted);
  font-size: 0.68rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.11em;
}

.reader-callout {
  margin: 1.05rem 0 0;
  border-left: 3px solid var(--gold);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--amber-soft);
  color: var(--amber);
  padding: 0.75rem 1rem;
  font-size: 0.88rem;
  line-height: 1.6;
}

/* --- math ------------------------------------------------------------------ */

.reader-math {
  margin-top: 0.4rem;
}

.reader-math-note {
  margin: 1rem 0 0.2rem;
  color: var(--ink-2);
  font-size: 0.93rem;
  line-height: 1.75;
}

.reader-math-display {
  margin: 0.2rem 0;
  padding: 0.3rem 0.1rem;
  overflow-x: auto;
  overflow-y: hidden;
}

.reader-math-display > code {
  display: block;
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  white-space: pre-wrap;
}

.reader-math-display .katex-display {
  margin: 0.4rem 0;
}

.reader-math-display .katex {
  font-size: 1.02em;
}

/* Inline math sits inside a sentence, so it must not add line height. Before
   KaTeX loads it shows the raw TeX in the fallback <code>. */
.reader-math-inline > code {
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.85em;
}

.reader-math-inline .katex {
  font-size: 1em;
}

/* --- lesson blocks --------------------------------------------------------- */

.reader-subhead {
  margin: 1.9rem 0 0.8rem;
  color: var(--ink);
  font-size: 1.45rem;
  font-weight: 750;
  line-height: 1.25;
  letter-spacing: 0;
}

h4.reader-subhead {
  font-size: 1.08rem;
  color: var(--ink-2);
}

/* The topic heading is the section label now, so a leading "###" stays a
   genuine sub-heading rather than being promoted to stand in for it. */
.reader-section > .reader-subhead:first-of-type {
  margin-top: 0.2rem;
}

.reader-block-list {
  display: grid;
  gap: 0.38rem;
  margin: 0 0 0.95rem;
}

.reader-block-list li::marker {
  color: var(--brand);
  font-weight: 700;
}

.reader-quote {
  margin: 1rem 0 1.1rem;
  border-left: 4px solid var(--brand);
  background: color-mix(in srgb, var(--brand-soft) 58%, var(--panel));
  border-radius: 0 8px 8px 0;
  padding: 0.85rem 1rem;
}

.reader-quote p:last-child {
  margin-bottom: 0;
}

/* Tables can be wider than the column, so they scroll inside their own wrapper
   rather than pushing the page sideways. */
.reader-table-wrap {
  margin: 1.05rem 0 1.25rem;
  overflow-x: auto;
  border: 1px solid var(--line-soft);
  border-radius: 8px;
}

.reader-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.96rem;
}

.reader-table th,
.reader-table td {
  padding: 0.72rem 0.95rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line-soft);
  color: var(--ink);
  line-height: 1.6;
}

.reader-table th {
  color: var(--ink);
  font-size: 0.84rem;
  font-weight: 750;
  text-transform: none;
  letter-spacing: 0;
  white-space: nowrap;
  background: color-mix(in srgb, var(--brand-soft) 68%, var(--panel));
}

.reader-table tbody tr:nth-child(even) {
  background: color-mix(in srgb, var(--surface-2) 45%, transparent);
}

.reader-figure {
  margin: 1.35rem 0 1.65rem;
  border: 1px solid var(--line-soft);
  border-radius: 10px;
  background: var(--panel);
  padding: 0.75rem;
}

.reader-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: calc(var(--radius) - 4px);
}

.reader-figure figcaption {
  margin-top: 0.65rem;
  color: var(--muted);
  font-size: 0.84rem;
  line-height: 1.5;
}

/* --- the module's slice of the problemset ---------------------------------- */

.reader-problems-section {
  border-top: 1px solid var(--line);
  padding-top: 2.1rem;
}

.reader-problems-section > h2 {
  color: var(--ink);
  font-size: 1.45rem;
  font-weight: 750;
  letter-spacing: 0;
  text-transform: none;
}


@media (max-width: 620px) {

}

.reader-problems-empty {
  margin: 0;
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  background: var(--surface-2);
  padding: 1.1rem 1.3rem;
  color: var(--muted);
  font-size: 0.95rem;
  line-height: 1.6;
}

.reader-problems-empty a {
  color: var(--brand-strong);
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}

.reader-problems-empty a:hover,
.reader-problems-empty a:focus-visible {
  text-decoration: underline;
  outline: none;
}

.reader-table tr:last-child td {
  border-bottom: 0;
}

.reader-answer {
  margin: 0 0 1.4rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--surface-2);
}

.reader-answer > summary {
  cursor: pointer;
  padding: 0.65rem 1rem;
  color: var(--brand);
  font-size: 0.78rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  list-style: none;
}

.reader-answer > summary::-webkit-details-marker {
  display: none;
}

.reader-answer > summary::before {
  content: "Show ";
}

.reader-answer[open] > summary::before {
  content: "Hide ";
}

.reader-answer-body {
  padding: 0.2rem 1.15rem 1rem;
  border-top: 1px solid var(--line-soft);
}

.reader-answer-body > *:last-child {
  margin-bottom: 0;
}

.module-list-more {
  color: var(--muted);
  font-style: italic;
}

/* --- code ------------------------------------------------------------------ */

.reader-code-block {
  margin: 1.05rem 0 1.25rem;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #f6f8fa;
  overflow: hidden;
}

.reader-code-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  border-bottom: 1px solid var(--line-soft);
  padding: 0.45rem 0.6rem 0.45rem 0.95rem;
  color: var(--muted-2);
  font-size: 0.68rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.09em;
}

.reader-code-copy {
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  background: none;
  color: var(--muted);
  font: inherit;
  padding: 0.15rem 0.5rem;
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease),
    border-color var(--t-fast) var(--ease);
}

.reader-code-copy:hover,
.reader-code-copy:focus-visible {
  border-color: var(--line);
  background: #fff;
  color: var(--brand-strong);
  outline: none;
}

.reader-code-block pre {
  margin: 0;
  max-height: 420px;
  overflow: auto;
  padding: 0.85rem 0;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.6;
}

.reader-code-block pre > span {
  display: grid;
  grid-template-columns: 2.2rem minmax(0, 1fr);
  gap: 0.7rem;
  padding: 0.02rem 0.9rem;
}

.reader-code-block pre b {
  color: var(--muted-2);
  font-weight: 400;
  text-align: right;
  user-select: none;
}

.reader-code-block code {
  white-space: pre;
}

/* --- problem cards ---------------------------------------------------------- */

.reader-focus-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  width: 100%;
  margin-top: 1.05rem;
  border: 1px solid var(--line);
  border-left: 3px solid var(--brand);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  padding: 0.85rem 1rem;
  text-align: left;
  cursor: pointer;
  text-decoration: none;
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.reader-focus-card:hover,
.reader-focus-card:focus-visible {
  border-color: var(--brand);
  background: var(--brand-soft);
  outline: none;
}

.reader-focus-copy strong,
.reader-focus-copy small,
.reader-focus-copy em {
  display: block;
}

.reader-focus-copy small {
  color: var(--brand-strong);
  font-size: 0.66rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.reader-focus-copy strong {
  margin-top: 0.25rem;
  font-size: 0.92rem;
}

.reader-focus-copy em {
  margin-top: 0.25rem;
  color: var(--muted);
  font-size: 0.84rem;
  font-style: normal;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.reader-focus-open {
  flex: 0 0 auto;
  color: var(--brand-strong);
  font-weight: 800;
  font-size: 0.82rem;
  white-space: nowrap;
}


/* --- prev / next ------------------------------------------------------------ */

.reader-pagenav {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.7rem;
  margin-top: 2.6rem;
  padding-top: 1.3rem;
  border-top: 1px solid var(--line-soft);
}

.reader-pagenav-card {
  display: grid;
  gap: 0.2rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  text-decoration: none;
  padding: 0.75rem 0.95rem;
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.reader-pagenav-card.next {
  text-align: right;
}

.reader-pagenav-card small {
  color: var(--muted-2);
  font-size: 0.66rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.reader-pagenav-card strong {
  font-size: 0.88rem;
  line-height: 1.35;
}

.reader-pagenav-card:hover,
.reader-pagenav-card:focus-visible {
  border-color: var(--brand-ring);
  background: var(--brand-soft);
  outline: none;
}

.reader-pagenav-card:hover strong {
  color: var(--brand-strong);
}

/* --- foot of the article ----------------------------------------------------- */

.reader-help {
  margin-top: 2.6rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--surface-2);
  padding: 1.25rem 1.4rem;
}

.reader-help strong {
  display: block;
  color: var(--ink);
  font-size: 1rem;
}

.reader-help p {
  margin: 0.35rem 0 0.75rem;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.6;
}

.reader-help a {
  color: var(--brand-strong);
  font-size: 0.92rem;
  font-weight: 700;
  text-decoration: none;
}

.reader-help a:hover,
.reader-help a:focus-visible {
  text-decoration: underline;
  outline: none;
}


.reader-nav-footer a:hover,
.reader-nav-footer a:focus-visible {
  color: var(--brand);
  outline: none;
}

/* ------------------------------- problem list ------------------------------ */

/* ----------------------- problems: banner + filter bar --------------------- */

.problems-banner {
  display: grid;
  justify-items: center;
  gap: var(--space-5);
  padding: 3.4rem var(--page-gutter) 3.6rem;
  background: var(--surface-2);
  border-bottom: 1px solid var(--line);
}

.problems-banner h1 {
  margin: 0;
  color: var(--brand);
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  letter-spacing: -0.02em;
}

.problems-search {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  width: min(100%, 620px);
  padding: 0.85rem 1.1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.problems-search:focus-within {
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-ring);
}

.problems-search svg {
  width: 20px;
  height: 20px;
  flex: none;
  fill: none;
  stroke: var(--muted);
  stroke-width: 2;
  stroke-linecap: round;
}

.problems-search input {
  flex: 1;
  min-width: 0;
  border: 0;
  background: none;
  color: var(--ink);
  font: inherit;
  font-size: 1rem;
}

.problems-search input:focus {
  outline: none;
}

.problems-controls {
  width: min(100% - var(--page-gutter), var(--max));
  margin: 0 auto;
  padding: var(--space-5) 0 var(--space-4);
  display: grid;
  gap: var(--space-4);
}

.problems-filter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: var(--space-3) var(--space-4);
}

.problems-sort-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 0.6rem;
}

.sort-button,
.sort-select {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  min-height: 40px;
  padding: 0 1rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  color: var(--ink-2);
  font: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.sort-button svg {
  width: 16px;
  height: 16px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.sort-button:hover,
.sort-select:hover {
  border-color: var(--brand);
  color: var(--brand);
}

.sort-select {
  padding-right: 0.6rem;
}

/* ------------------------- problems: card grid ---------------------------- */

.problem-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(255px, 1fr));
  gap: var(--space-4);
}

.pcard {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  padding: 1.4rem 1.4rem 1.5rem;
  cursor: pointer;
  transition: border-color var(--t-mid) var(--ease), transform var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease);
}

/* Overlay that makes the entire card one click target. */
.pcard-link {
  position: absolute;
  inset: 0;
  z-index: 1;
  border: 0;
  border-radius: inherit;
  background: none;
  padding: 0;
  cursor: pointer;
}

.pcard-link:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 2px;
}

/* Controls and module links stay clickable above the overlay. */
.pcard-status,
.pcard-appears a {
  position: relative;
  z-index: 2;
}

.pcard:hover .pcard-title {
  color: var(--brand);
}

.pcard:hover {
  border-color: color-mix(in srgb, var(--brand) 40%, var(--line));
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.pcard.flash {
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-ring);
}

/* Only holds the status toggle now, so it sits in the corner instead of taking
   a row of its own — that lets the title start at the top of the card. */
.pcard-top {
  position: absolute;
  top: 1.25rem;
  right: 1.4rem;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Coding vs Theory sits beside the difficulty chip and borrows its shape from
   .problem-chip, so the footer reads as one row of tags. */
.problem-chip.pcard-type.type-coding {
  color: var(--brand-strong);
  border-color: color-mix(in srgb, var(--brand) 40%, transparent);
  background: var(--brand-soft);
}

.problem-chip.pcard-type.type-theory {
  color: var(--clay);
  border-color: color-mix(in srgb, var(--clay) 40%, transparent);
  background: var(--clay-soft);
}

.pcard-status {
  width: 26px;
  height: 26px;
  flex: none;
  border: 0;
  border-radius: 50%;
  background: var(--fill-shape);
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), box-shadow var(--t-fast) var(--ease);
}

.pcard-status:hover {
  box-shadow: 0 0 0 3px var(--brand-ring);
}

.pcard-status[data-status="complete"] {
  background: var(--green);
}

/* Every card is the same height, so the two variable-length pieces are pinned:
   the title always occupies exactly two lines and the module link exactly one,
   each truncated with an ellipsis when it would run longer. */
.pcard-title {
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
  line-clamp: 2;
  overflow: hidden;
  min-height: 2.6em;
  margin: 0;
  /* keeps a long first line clear of the corner status button */
  padding-right: 2.1rem;
  font-size: 1.02rem;
  line-height: 1.3;
  letter-spacing: -0.01em;
  transition: color var(--t-fast) var(--ease);
}


.pcard-appears {
  color: var(--muted);
  font-size: 0.86rem;
}

.pcard-appears ul {
  margin: 0.4rem 0 0;
  padding-left: 1.1rem;
  line-height: 1.6;
}

.pcard-appears li {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.pcard-appears a {
  color: var(--brand);
  text-decoration: none;
  transition: color var(--t-fast) var(--ease);
}

.pcard-appears a:hover {
  color: var(--brand-strong);
  text-decoration: underline;
}

.pcard-foot {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-top: auto;
  padding-top: 0.9rem;
}

.problem-chip {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  border: 1px solid var(--line);
  color: var(--muted);
  background: var(--surface-2);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.14rem 0.55rem;
  white-space: nowrap;
}

.problem-chip.difficulty-easy {
  color: var(--green);
  border-color: color-mix(in srgb, var(--green) 40%, transparent);
  background: var(--green-soft);
}

.problem-chip.difficulty-normal {
  color: var(--ochre);
  border-color: color-mix(in srgb, var(--ochre) 40%, transparent);
  background: var(--ochre-soft);
}

.problem-chip.difficulty-hard {
  color: var(--coral);
  border-color: color-mix(in srgb, var(--coral) 40%, transparent);
  background: var(--coral-soft);
}

.problem-chip.difficulty-mixed {
  color: var(--clay);
  border-color: color-mix(in srgb, var(--clay) 40%, transparent);
  background: var(--clay-soft);
}

.problem-chip.difficulty-medium {
  color: var(--ochre);
  border-color: color-mix(in srgb, var(--ochre) 40%, transparent);
  background: var(--ochre-soft);
}

.problem-chip.difficulty-very-hard {
  color: #991b1b;
  border-color: color-mix(in srgb, #991b1b 40%, transparent);
  background: #fef2f2;
}

.reader-link-list {
  margin: 0.7rem 0 0;
  padding-left: 1.15rem;
  display: grid;
  gap: 0.4rem;
}

.reader-link-list a {
  color: var(--brand);
  font-weight: 600;
  text-decoration: none;
}

.reader-link-list a:hover {
  text-decoration: underline;
}

.reader-link-list small {
  color: var(--muted);
  margin-left: 0.35rem;
}

.reader-similar-stack {
  display: grid;
  gap: 0.65rem;
}

.reader-similar-card {
  text-decoration: none;
  margin-top: 0;
}

.reader-similar-stack .reader-similar-card:first-child {
  margin-top: 1.15rem;
}

.reader-similar-card .problem-chip {
  flex-shrink: 0;
}

/* ---------------------------------- search --------------------------------- */

.search-results {
  display: grid;
  gap: 0.8rem;
}

.search-result-card {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 1rem;
  align-items: center;
  border: 1px solid var(--line);
  border-left: 4px solid var(--brand);
  border-radius: var(--radius-lg);
  background: var(--panel);
  padding: 1.05rem;
  transition: transform var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease);
}

.search-result-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.search-result-card[data-search-type="lesson"] {
  border-left-color: var(--stage-advanced);
}

.search-result-card[data-search-type="problem"] {
  border-left-color: var(--stage-round2);
}

.search-result-card[data-search-type="resource"] {
  border-left-color: var(--stage-camp);
}

.search-result-card h3 {
  margin: 0.2rem 0 0;
  letter-spacing: -0.01em;
}

.search-result-card p {
  color: var(--muted);
  margin: 0.35rem 0 0;
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0.45rem 0;
}

.tag-row span {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.16rem 0.5rem;
}

.problem-answer {
  border-left: 3px solid var(--green);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--green-soft);
  color: var(--ink);
  padding: 0.6rem 0.75rem;
  margin: 0.55rem 0;
}

/* --------------------------------- contests -------------------------------- */

.contest-card {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  box-shadow: var(--shadow-sm);
  margin-top: 1rem;
  padding: 1.15rem;
}

.contest-head {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.contest-head h3,
.contest-card h4 {
  margin: 0;
}

.contest-head p {
  color: var(--muted);
  margin: 0.35rem 0 0;
}

.contest-timer {
  min-width: 96px;
  height: 48px;
  display: grid;
  place-items: center;
  border-radius: var(--radius);
  background: var(--ink);
  color: white;
  font-family: var(--font-mono);
  font-weight: 600;
  letter-spacing: 0.04em;
}

.contest-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin: 1rem 0;
}

.contest-problems {
  display: grid;
  gap: 0.65rem;
  padding-left: 0;
  list-style: none;
}

.contest-problems label {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.6rem;
  align-items: start;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0.75rem;
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.contest-problems label:hover {
  border-color: var(--brand);
}

.contest-problems input {
  accent-color: var(--brand);
}

.contest-problems span,
.contest-problems strong {
  display: block;
}

.contest-problems span {
  color: var(--muted);
}

/* ------------------------------ settings & forms --------------------------- */

.scratchpad {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  padding: 0.85rem;
  resize: vertical;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  transition: border-color var(--t-fast) var(--ease), box-shadow var(--t-fast) var(--ease);
}

.scratchpad:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-ring);
}

.helper-text {
  color: var(--muted);
  font-size: 0.86rem;
  margin: 0.55rem 0 0;
}

.text-input {
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  padding: 0.5rem 0.75rem;
  transition: border-color var(--t-fast) var(--ease), box-shadow var(--t-fast) var(--ease);
}

.text-input:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-ring);
}

.time-pill {
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 600;
  white-space: nowrap;
}

.empty-state {
  border: 1.5px dashed var(--line);
  border-radius: var(--radius-lg);
  color: var(--muted);
  padding: 1.5rem;
  text-align: center;
}

.split-section {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(280px, 0.85fr);
  gap: 1.1rem;
  align-items: stretch;
}

.accent-panel {
  background: var(--surface-2);
}

.accent-panel .link-list {
  margin-top: 0.9rem;
}

.sponsor-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: clamp(1.2rem, 4vw, 2.5rem);
  align-items: center;
  margin-top: 1.1rem;
  padding: clamp(1.35rem, 3vw, 2rem);
  border: 1px solid color-mix(in srgb, var(--brand) 28%, var(--line));
  border-radius: var(--radius-lg);
  background:
    linear-gradient(90deg, rgba(184, 78, 48, 0.08), transparent 36%),
    var(--panel);
  box-shadow: var(--shadow-md);
}

.sponsor-panel h2 {
  margin: 0;
  color: var(--brand);
  font-size: clamp(1.55rem, 3vw, 2.25rem);
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.sponsor-panel p:not(.eyebrow) {
  max-width: 760px;
  margin: 0.75rem 0 0;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.65;
}

.sponsor-panel .button {
  white-space: nowrap;
}

.sponsor-info-note {
  margin: 0.65rem 0 0;
  text-align: right;
}

.sponsor-info-note a {
  color: var(--brand-strong);
  font-size: 0.88rem;
  font-weight: 700;
  text-decoration: none;
}

.sponsor-info-note a:hover,
.sponsor-info-note a:focus-visible {
  text-decoration: underline;
}

.method-list {
  margin: 0;
  padding-left: 1.25rem;
}

.method-list li {
  padding-left: 0.3rem;
}

.method-list li + li {
  margin-top: 0.9rem;
}

.method-list li::marker {
  color: var(--brand);
  font-weight: 700;
}

.method-list strong {
  display: block;
}

/* ---------------------------- resources & extras --------------------------- */

.link-list,
.checklist {
  display: grid;
  gap: 0.7rem;
}

.link-list a,
.check-item {
  display: grid;
  gap: 0.15rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  padding: 0.85rem;
  text-decoration: none;
  transition: border-color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease);
}

.link-list a:hover,
.link-list a:focus-visible {
  border-color: var(--brand);
  transform: translateY(-2px);
  outline: none;
}

.link-list span {
  font-weight: 700;
}

.link-list small {
  color: var(--muted);
}

.timeline {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.9rem;
}

.timeline article {
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  padding: 1.05rem;
  overflow: hidden;
}

.timeline article::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 4px;
  background: var(--brand);
}

.timeline article:nth-child(2)::before,
.timeline article:nth-child(5)::before {
  background: var(--stage-advanced);
}

.timeline article:nth-child(3)::before {
  background: var(--stage-round2);
}

.timeline span {
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.07em;
}

.timeline h3 {
  font-size: 1rem;
  margin-top: 0.35rem;
}

.timeline p {
  color: var(--muted);
  margin: 0.45rem 0 0;
  font-size: 0.9rem;
}

.resource-card a {
  margin-top: auto;
  color: var(--brand-strong);
  font-weight: 700;
  text-decoration: none;
  transition: color var(--t-fast) var(--ease);
}

.resource-card a:hover,
.resource-card a:focus-visible {
  color: var(--brand);
  outline: none;
}

.check-item {
  grid-template-columns: auto 1fr;
  align-items: start;
  cursor: pointer;
}

.check-item input {
  width: 18px;
  height: 18px;
  margin-top: 0.18rem;
  accent-color: var(--brand);
}

.check-item span {
  font-weight: 600;
}

details {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
  padding: 0.95rem 1.05rem;
}

details + details {
  margin-top: 0.7rem;
}

summary {
  cursor: pointer;
  font-weight: 700;
}

details p {
  color: var(--muted);
  margin: 0.65rem 0 0;
}

/* ---------------------------------- footer --------------------------------- */

.site-footer {
  width: min(100% - var(--page-gutter), var(--max));
  margin: 0 auto;
  padding: 2.2rem 0 3rem;
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  color: var(--muted);
  border-top: 1px solid var(--line);
}

.site-footer p {
  margin: 0.3rem 0 0;
  max-width: 620px;
  line-height: 1.6;
}

.site-footer a {
  color: var(--brand-strong);
  font-weight: 700;
}

/* ---------------------------------- pager ----------------------------------- */

.pager {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 0.35rem;
  margin-top: 1.1rem;
}

.pager-button {
  min-width: 38px;
  height: 38px;
  padding: 0 0.6rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--panel);
  color: var(--muted);
  font-weight: 700;
  cursor: pointer;
  transition: color var(--t-fast) var(--ease), background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.pager-button:hover:not(:disabled),
.pager-button:focus-visible:not(:disabled) {
  color: var(--brand-strong);
  background: var(--brand-soft);
  border-color: var(--brand-ring);
  outline: none;
}

.pager-button.active {
  color: white;
  background: var(--ink);
  border-color: var(--ink);
}

.pager-button:disabled {
  opacity: 0.4;
  cursor: default;
}

.pager-gap {
  color: var(--muted-2);
  padding: 0 0.2rem;
  user-select: none;
}

.pager-info {
  margin: 0 0 0.75rem;
  color: var(--muted);
  font-size: 0.85rem;
  font-weight: 600;
}

/* --------------------------------- planner ---------------------------------- */

.planner-layout {
  display: grid;
  grid-template-columns: minmax(300px, 5fr) 7fr;
  gap: var(--space-4);
  align-items: start;
}

.planner-library {
  display: grid;
  gap: 0.55rem;
  max-height: 62svh;
  overflow-y: auto;
  padding: 2px;
  margin-top: 0.4rem;
}

.plan-block {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 0.7rem;
  border: 1px solid var(--line);
  border-left: 4px solid var(--brand);
  border-radius: var(--radius);
  background: var(--panel);
  padding: 0.6rem 0.75rem;
  cursor: grab;
  transition: box-shadow var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease), opacity var(--t-fast) var(--ease);
}

.plan-block:hover {
  box-shadow: var(--shadow-sm);
  border-color: color-mix(in srgb, var(--brand) 35%, var(--line));
  border-left-color: var(--brand);
}

.plan-block.plan-type-problem {
  border-left-color: var(--stage-round2);
}

.plan-block.plan-type-problem:hover {
  border-left-color: var(--stage-round2);
}

.plan-block.in-plan {
  opacity: 0.55;
  cursor: default;
}

.plan-block.dragging {
  opacity: 0.4;
}

.plan-grip {
  width: 10px;
  height: 18px;
  border-left: 2px solid var(--muted-2);
  border-right: 2px solid var(--muted-2);
}

.plan-block-copy {
  min-width: 0;
}

.plan-block-copy strong {
  display: block;
  font-size: 0.92rem;
  line-height: 1.35;
}

.plan-block-copy small {
  display: block;
  margin-top: 0.1rem;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 600;
}

.plan-add {
  width: 30px;
  height: 30px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--ink);
  font-weight: 800;
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.plan-add:hover:not(:disabled),
.plan-add:focus-visible:not(:disabled) {
  background: var(--brand);
  border-color: var(--brand);
  color: white;
  outline: none;
}

.plan-add:disabled {
  color: var(--green);
  border-color: transparent;
  background: var(--green-soft);
  cursor: default;
}

.planner-board-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
}

.planner-board-tools {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.planner-board {
  list-style: none;
  margin: 1rem 0 0;
  padding: 0.65rem;
  display: grid;
  gap: 0.55rem;
  align-content: start;
  min-height: 340px;
  border: 2px dashed var(--line);
  border-radius: var(--radius-lg);
  background: var(--paper);
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.planner-board.drag-over {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.plan-order {
  width: 26px;
  height: 26px;
  border-radius: 999px;
  display: grid;
  place-items: center;
  background: var(--surface-2);
  color: var(--muted);
  font-weight: 800;
  font-size: 0.75rem;
}

.plan-actions {
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

.plan-tool {
  min-width: 30px;
  height: 30px;
  padding: 0 0.5rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--panel);
  color: var(--muted);
  font: inherit;
  font-size: 0.8rem;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  transition: color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.plan-tool:hover:not(:disabled),
.plan-tool:focus-visible:not(:disabled) {
  color: var(--brand);
  border-color: var(--brand);
  outline: none;
}

.plan-tool:disabled {
  opacity: 0.35;
  cursor: default;
}

.plan-remove:hover:not(:disabled),
.plan-remove:focus-visible:not(:disabled) {
  color: var(--coral);
  border-color: var(--coral);
}

.planner-empty {
  display: grid;
  gap: 0.3rem;
  padding: 2.6rem 1rem;
  text-align: center;
  color: var(--muted);
}

.planner-empty strong {
  color: var(--ink-2);
}

/* ------------------------------- media queries ----------------------------- */

@media (max-width: 1080px) {
  .timeline {
    grid-template-columns: repeat(2, 1fr);
  }

  .guide-shell,
  .planner-layout,
  .dash-columns {
    grid-template-columns: 1fr;
  }

  .kpi-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .planner-library {
    max-height: 46svh;
  }

  .side-panel {
    position: static;
    grid-template-columns: repeat(3, 1fr);
  }

  .module-grid,
  .dashboard-grid,
  .status-summary,
  .module-reader,
  .resource-grid,
  .route-grid,
  .section-link-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .reader-sidebar {
    position: static;
  }

  .dash-wide {
    grid-column: span 1;
  }

  .usaco-reader {
    grid-template-columns: 320px minmax(1.5rem, 0.55fr) minmax(0, 896px) minmax(1.5rem, 1.45fr);
  }

  .usaco-reader.nav-collapsed {
    grid-template-columns: 0 minmax(1.5rem, 0.8fr) minmax(0, 720px) minmax(1.5rem, 1.2fr);
  }

  .reader-sidenav {
    grid-column: 1;
  }

  .reader-article {
    grid-column: 3;
  }


  .dashboard-shell {
    width: min(100% - var(--page-gutter), 900px);
  }

  .activity-card {
    grid-template-columns: 1fr;
  }

  .dash-hero {
    grid-template-columns: 1fr;
    align-items: stretch;
  }

  .dash-hero .dashboard-continue {
    width: 100%;
  }
}

@media (max-width: 760px) {
  .nav-toggle {
    display: inline-flex;
  }

  .nav-links {
    position: absolute;
    left: 1rem;
    right: 1rem;
    top: calc(var(--header-h) + 8px);
    display: none;
    flex-direction: column;
    align-items: stretch;
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    padding: 0.5rem;
  }

  .nav-divider {
    display: none;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a,
  .nav-menu summary,
  .nav-login-button {
    border-radius: 999px;
  }

  .nav-menu,
.nav-menu-panel {
    width: 100%;
  }

  .nav-menu-panel {
    position: static;
    min-width: 0;
    margin: 0.2rem 0 0.4rem;
    box-shadow: none;
    border-color: var(--line-soft);
    background: var(--surface-2);
  }

  .nav-menu[open] .nav-menu-panel {
    animation: none;
  }

  .nav-links.open {
    animation: dropdown-in var(--t-mid) var(--ease);
    transform-origin: top center;
  }

  .hero {
    min-height: min(620px, calc(100svh - 112px));
  }

  .hero-content {
    padding-top: 2.2rem;
    padding-bottom: 3.2rem;
  }

  .side-panel,
.dashboard-grid,
.status-summary,
.module-reader,
.module-grid,
.resource-grid,
.route-grid,
.section-link-grid,
.table-filter-grid,
.split-section,
.sponsor-panel,
.timeline,
.site-footer {
  grid-template-columns: 1fr;
}

  .sponsor-panel .button {
    justify-self: start;
  }

  .sponsor-info-note {
    text-align: left;
  }

  .page-hero {
    align-items: stretch;
    flex-direction: column;
  }

  .module-actions,
  .reader-header,
  .reader-nav,
  .contest-head,
  .search-result-card {
    align-items: stretch;
    flex-direction: column;
  }

  .search-result-card {
    display: flex;
  }

  .status-select {
    max-width: none;
    width: 100%;
  }

  .problems-filter-grid {
    grid-template-columns: 1fr;
  }

  .site-footer {
    display: grid;
  }

  .stage-progress-card {
    grid-template-columns: 1fr;
    gap: 1.1rem;
  }

  .chapter-card-head {
    flex-direction: column;
    gap: 0.5rem;
  }

  .chapter-card-head .chapter-meter {
    justify-content: flex-start;
    margin-top: 0;
  }

  .topic-row {
    grid-template-columns: 30px minmax(0, 1fr);
  }

  .topic-row .mini-status {
    grid-column: 2;
    justify-self: start;
    margin-top: 0;
  }

  body[data-page="module"] {
    --reader-zoom: 1;
  }

  .usaco-reader {
    display: block;
  }

  .reader-sidenav {
    position: static;
    height: auto;
    border-right: 0;
    border-bottom: 1px solid var(--line-soft);
  }

  .reader-nav-scroll {
    max-height: 320px;
  }

  .reader-article {
    width: min(100% - 2rem, 680px);
    margin: 0 auto;
    padding: 1.7rem 0 4rem;
  }


  .reader-toolbar .status-select {
    max-width: none;
    width: auto;
  }

  /* Prev/Next stay reachable; the trail itself would wrap to three lines. */
  .reader-crumbs {
    display: none;
  }

  .reader-topbar {
    justify-content: space-between;
    padding-bottom: 1.2rem;
  }

  .reader-head h1 {
    font-size: 1.7rem;
  }

  .reader-pagenav {
    grid-template-columns: 1fr;
  }

  .reader-pagenav-card.next {
    text-align: left;
  }

  .reader-problem-card {
    align-items: stretch;
    grid-template-columns: 1fr;
    flex-direction: column;
  }

  .dashboard-continue {
    width: 100%;
  }

  .activity-card {
    overflow-x: auto;
  }
}

@media (max-width: 460px) {
  :root {
    --page-gutter: 1rem;
  }

  .panel,
  .progress-box,
  .side-section {
    padding: 0.95rem;
  }

  .hero-actions .button {
    width: 100%;
  }

  .division-hero p {
    margin-top: 0.7rem;
    font-size: 0.92rem;
  }

  .stage-switch {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    border-radius: 999px;
  }

  .stage-switch a {
    text-align: center;
    border-radius: 999px;
    padding: 0.5rem 0.4rem;
  }

  .stage-progress-card {
    padding: 1rem;
  }

  .topic-row {
    padding: 0.8rem 1rem;
  }

  .chapter-card-head {
    padding: 1rem;
  }

  .division-hero h1 {
    font-size: 2rem;
  }

  .activity-card {
    padding: 1rem;
  }

  .activity-heatmap {
    grid-template-rows: repeat(7, 9px);
    grid-auto-columns: 9px;
    gap: 2px;
  }

  .activity-square {
    width: 9px;
    height: 9px;
  }
}

/* ------------------------------ notebook editor ---------------------------- */
/* Colab-style cells: run-button gutter, syntax-highlighted code, compact type. */

:root {
  --code-bg: #f9f9fb;
  --code-font-size: 12px;
  --code-line-height: 1.45;
  /* Warm syntax theme: no blue/purple tokens. Strings and comments keep their
     conventional red/green so code stays scannable. */
  --tok-kw: #b84e30;
  --tok-str: #a31515;
  --tok-com: #007400;
  --tok-num: #098658;
  --tok-fn: #795e26;
  --tok-def: #a8442a;
  --tok-dec: #a06a10;
  --tok-blt: #7d7c26;
  --tok-op: #96704a;
}

body[data-page="editor"] .page-hero h1 {
  font-size: clamp(1.5rem, 3.4vw, 2.3rem);
}

body[data-page="editor"] .page-hero p:not(.eyebrow) {
  font-size: 0.92rem;
  margin-top: 0.5rem;
  font-family: var(--font-mono);
  color: var(--muted);
}

.editor-panel {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.editor-toolbar {
  position: sticky;
  top: calc(var(--header-h) + 12px);
  z-index: 5;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: color-mix(in srgb, var(--panel) 88%, transparent);
  backdrop-filter: blur(10px) saturate(1.3);
  -webkit-backdrop-filter: blur(10px) saturate(1.3);
  box-shadow: var(--shadow-sm);
}

.editor-toolbar .button {
  min-height: 34px;
  padding: 6px 14px;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  box-shadow: none;
}

.editor-toolbar .button svg {
  width: 14px;
  height: 14px;
}

.editor-toolbar .button-primary {
  box-shadow: var(--shadow-brand);
}

.editor-toolbar .button:hover,
.editor-toolbar .button:focus-visible {
  transform: translateY(-1px);
}

.editor-kernel {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--muted);
  padding: 5px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  transition: color var(--t-mid) var(--ease), border-color var(--t-mid) var(--ease), background var(--t-mid) var(--ease);
}

.editor-kernel::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--green);
  flex: none;
}

.editor-kernel.busy {
  color: var(--amber);
  border-color: color-mix(in srgb, var(--amber) 45%, transparent);
  background: var(--amber-soft);
}

.editor-kernel.busy::before {
  background: var(--amber);
  animation: kernel-pulse 1.1s ease-in-out infinite;
}

@keyframes kernel-pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.35; transform: scale(0.7); }
}

.editor-note {
  font-size: 0.8rem;
  line-height: 1.55;
  color: var(--ink-2);
  background: var(--ochre-soft);
  border: 1px solid color-mix(in srgb, var(--ochre) 22%, transparent);
  border-left: 3px solid var(--ochre);
  border-radius: var(--radius-sm);
  padding: 9px 14px;
}

.editor-cells {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

/* ------ cell shell: [gutter | main], Colab-style hover/selection frame ----- */

.editor-cell {
  display: flex;
  gap: 8px;
  padding: 6px 8px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  animation: cell-in var(--t-slow) var(--ease) backwards;
  transition: border-color var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease), background var(--t-mid) var(--ease);
}

@keyframes cell-in {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.editor-cell:hover {
  border-color: var(--line);
}

.editor-cell-code:focus-within {
  border-color: color-mix(in srgb, var(--brand) 45%, var(--line));
  box-shadow: var(--shadow-sm);
}

.cell-gutter {
  flex: none;
  width: 38px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding-top: 3px;
}

.cell-main {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.cell-run {
  width: 27px;
  height: 27px;
  padding: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--muted);
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease), box-shadow var(--t-fast) var(--ease);
}

.cell-run svg {
  width: 13px;
  height: 13px;
  fill: currentColor;
  margin-left: 1px;
}

.cell-run:hover,
.cell-run:focus-visible {
  background: var(--brand);
  border-color: var(--brand);
  color: #fff;
  transform: scale(1.08);
  box-shadow: 0 4px 12px -3px color-mix(in srgb, var(--brand) 60%, transparent);
  outline: none;
}

.editor-cell.running .cell-run {
  color: transparent;
  border-color: var(--line);
  background: var(--panel);
  pointer-events: none;
  position: relative;
}

.editor-cell.running .cell-run::after {
  content: "";
  position: absolute;
  inset: 4px;
  border-radius: 50%;
  border: 2px solid color-mix(in srgb, var(--brand) 25%, transparent);
  border-top-color: var(--brand);
  animation: cell-spin 700ms linear infinite;
}

@keyframes cell-spin {
  to { transform: rotate(360deg); }
}

.cell-count {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  color: var(--muted-2);
  letter-spacing: -0.03em;
  user-select: none;
}

/* ------------------ code area: highlight layer + textarea ------------------ */

.cell-editor {
  position: relative;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm);
  background: var(--code-bg);
  overflow: hidden;
  transition: border-color var(--t-mid) var(--ease);
}

.editor-cell-code:focus-within .cell-editor {
  border-color: color-mix(in srgb, var(--brand) 55%, var(--line));
}

.editor-highlight,
.editor-code {
  font-family: var(--font-mono);
  font-size: var(--code-font-size);
  line-height: var(--code-line-height);
  letter-spacing: normal;
  tab-size: 4;
  white-space: pre-wrap;
  overflow-wrap: break-word;
  word-break: break-word;
  padding: 8px 12px;
  margin: 0;
  border: none;
}

.editor-highlight {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
  color: var(--ink);
}

.editor-highlight code {
  font: inherit;
  background: none;
  padding: 0;
  border: none;
}

.editor-code {
  position: relative;
  z-index: 1;
  display: block;
  width: 100%;
  resize: vertical;
  min-height: 38px;
  background: transparent;
  color: transparent;
  caret-color: var(--ink);
}

.editor-code:focus {
  outline: none;
}

.editor-code::selection {
  background: color-mix(in srgb, var(--brand) 22%, transparent);
  color: transparent;
}

/* Colab-ish token colors (light + dark via tokens above) */
.tok-kw { color: var(--tok-kw); font-weight: 600; }
.tok-str { color: var(--tok-str); }
.tok-com { color: var(--tok-com); font-style: italic; }
.tok-num { color: var(--tok-num); }
.tok-fn { color: var(--tok-fn); }
.tok-def { color: var(--tok-def); font-weight: 600; }
.tok-dec { color: var(--tok-dec); }
.tok-blt { color: var(--tok-blt); }
.tok-op { color: var(--tok-op); }

/* --------------------------------- output ---------------------------------- */

.editor-output {
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm);
  background: var(--panel);
  padding: 7px 12px;
  max-height: 420px;
  overflow: auto;
  animation: output-in var(--t-mid) var(--ease);
}

@keyframes output-in {
  from { opacity: 0; transform: translateY(-3px); }
  to { opacity: 1; transform: translateY(0); }
}

.editor-output pre {
  margin: 2px 0;
  font-family: var(--font-mono);
  font-size: 11.5px;
  line-height: 1.45;
  white-space: pre-wrap;
  word-break: break-word;
}

.editor-output-error {
  color: var(--coral);
}

.editor-output canvas {
  max-width: 100%;
  margin: 8px 0;
}

/* ------------------------------ markdown cells ----------------------------- */

.editor-cell-markdown {
  background: transparent;
}

.editor-cell-markdown .editor-md {
  padding: 2px 4px;
  font-size: 0.92rem;
}

.editor-md h2,
.editor-md h3,
.editor-md h4 {
  font-family: var(--font-display);
  margin: 12px 0 6px;
  letter-spacing: -0.015em;
}

.editor-md h2 { font-size: 1.3rem; }
.editor-md h3 { font-size: 1.05rem; }
.editor-md p { margin: 6px 0; line-height: 1.55; }
.editor-md ul { margin: 6px 0 6px 20px; line-height: 1.55; }

.editor-md code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--surface-2);
  border: 1px solid var(--line-soft);
  border-radius: 4px;
  padding: 1px 5px;
}

.editor-md .md-code {
  background: var(--code-bg);
  color: var(--ink);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm);
  padding: 8px 12px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: var(--code-font-size);
  line-height: var(--code-line-height);
}

.editor-md .md-code code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

.editor-solution {
  border-color: color-mix(in srgb, var(--brand) 30%, var(--line));
  background: var(--brand-soft);
}

.editor-solution summary {
  color: var(--brand-strong);
  font-weight: 700;
  user-select: none;
}

.editor-solution[open] summary {
  margin-bottom: 0.5rem;
}

.editor-solution .md-code {
  background: var(--panel);
}

@media (max-width: 640px) {
  .editor-kernel {
    margin-left: 0;
    width: 100%;
    justify-content: center;
  }

  .editor-cell {
    padding: 4px 2px;
    gap: 5px;
  }

  .cell-gutter {
    width: 30px;
  }

  .cell-run {
    width: 24px;
    height: 24px;
  }
}

/* --------------------------------- about ---------------------------------- */

.about-hero {
  position: relative;
  overflow: hidden;
  border-bottom: 1px solid var(--line-soft);
  background:
    linear-gradient(90deg, rgba(184, 78, 48, 0.08), transparent 34%),
    var(--paper);
}

.about-hero::before {
  content: "";
  position: absolute;
  inset: auto 0 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(184, 78, 48, 0.34), transparent);
}

.about-hero-inner {
  width: min(100% - var(--page-gutter), 980px);
  margin: 0 auto;
  padding: clamp(3rem, 6vw, 4.75rem) 0 clamp(2rem, 4vw, 3rem);
  text-align: center;
}

.about-hero h1 {
  margin: 0 auto;
  max-width: 860px;
  color: var(--brand);
  font-size: clamp(2rem, 4.6vw, 3.6rem);
  font-weight: 800;
  letter-spacing: -0.025em;
  line-height: 1.04;
}

.about-hero p:not(.eyebrow) {
  margin: 1rem auto 0;
  max-width: 52rem;
  color: var(--ink-2);
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.55;
}

.about-team-wrap {
  width: min(100% - var(--page-gutter), 1120px);
  margin: 0 auto;
  padding: clamp(2.2rem, 5vw, 3.5rem) 0 clamp(4rem, 8vw, 6rem);
}

.about-team-wrap .section-heading.centered {
  max-width: none;
  margin-inline: auto;
}

.section-heading.centered {
  display: grid;
  justify-items: center;
  text-align: center;
}

.section-heading.centered h2 {
  width: fit-content;
}

.section-heading.centered h2::after {
  left: 50%;
  transform: translateX(-50%);
}

.team-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 20rem));
  justify-content: center;
  gap: clamp(1.4rem, 4vw, 2.4rem);
  margin-top: 1.8rem;
}

.team-card {
  position: relative;
  display: grid;
  justify-items: center;
  min-height: 24rem;
  padding: 2.4rem 2rem 2rem;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow-md);
  text-align: center;
  transition: border-color var(--t-mid) var(--ease), box-shadow var(--t-mid) var(--ease), transform var(--t-mid) var(--ease);
}

.team-card:hover,
.team-card:focus-within {
  transform: translateY(-4px);
  border-color: color-mix(in srgb, var(--brand) 42%, var(--line));
  box-shadow: 0 24px 56px -24px rgba(184, 78, 48, 0.46), var(--shadow-md);
}

.team-photo-placeholder {
  width: clamp(8.25rem, 18vw, 11rem);
  aspect-ratio: 1;
  border: 1px dashed color-mix(in srgb, var(--brand) 45%, var(--line));
  border-radius: 50%;
  background:
    linear-gradient(135deg, rgba(184, 78, 48, 0.12), rgba(238, 232, 220, 0.45)),
    var(--surface-2);
  box-shadow: inset 0 0 0 8px rgba(255, 255, 255, 0.62);
}

.team-card-body {
  margin-top: 1.4rem;
}

.team-card h3 {
  margin: 0;
  color: var(--ink);
  font-size: clamp(1.35rem, 2.8vw, 2rem);
  letter-spacing: 0;
  line-height: 1.12;
}

.team-position {
  margin: 0.45rem 0 0;
  color: var(--brand-strong);
  font-size: 0.88rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.team-description {
  margin: 0.9rem auto 0;
  max-width: 18rem;
  color: var(--muted);
  font-size: 0.98rem;
  line-height: 1.55;
}

.team-links {
  display: flex;
  gap: 0.7rem;
  margin-top: 1.45rem;
  opacity: 0;
  transform: translateY(8px);
  transition: opacity var(--t-mid) var(--ease), transform var(--t-mid) var(--ease);
}

.team-card:hover .team-links,
.team-card:focus-within .team-links {
  opacity: 1;
  transform: translateY(0);
}

.team-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.75rem;
  height: 2.75rem;
  border: 1px solid color-mix(in srgb, var(--brand) 32%, var(--line));
  border-radius: 50%;
  background: var(--paper);
  color: var(--brand-strong);
  box-shadow: var(--shadow-sm);
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease);
}

.team-links a:hover,
.team-links a:focus-visible {
  transform: translateY(-2px);
  background: var(--brand);
  color: #ffffff;
}

.team-links svg {
  width: 1.35rem;
  height: 1.35rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.9;
  stroke-linecap: round;
  stroke-linejoin: round;
}

@media (hover: none) {
  .team-links {
    opacity: 1;
    transform: none;
  }
}

@media (max-width: 1020px) {
  .team-grid {
    grid-template-columns: repeat(2, minmax(0, 22rem));
  }
}

@media (max-width: 760px) {
  .about-hero-inner {
    text-align: left;
  }

  .about-hero h1,
  .about-hero p:not(.eyebrow) {
    margin-left: 0;
  }

  .team-grid {
    grid-template-columns: 1fr;
  }

  .team-card {
    min-height: 25rem;
  }
}


/* ------------------------------- splash (home) ------------------------------ */

body[data-page="home"] {
  --home-header: #111827;
  --home-header-line: rgba(255, 255, 255, 0.08);
  --home-text: #f8fafc;
  --home-muted: #c7ccd6;
  --home-link: #d8dde8;
  --home-link-hover: #ffffff;
  background: var(--paper);
  color: var(--ink);
}

body[data-page="home"] .site-header {
  position: fixed;
  left: 0;
  right: 0;
  width: 100%;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid rgba(17, 24, 39, 0.08);
  box-shadow: 0 12px 36px rgba(17, 24, 39, 0.06);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}

body[data-page="home"] .brand {
  color: var(--ink);
}

body[data-page="home"] .brand-mark {
  box-shadow: 0 0 0 2px rgba(184, 78, 48, 0.14), 0 10px 24px rgba(17, 24, 39, 0.12);
}

body[data-page="home"] .brand strong {
  color: var(--ink);
  font-size: 1.08rem;
}

body[data-page="home"] .brand small {
  color: var(--muted);
}

body[data-page="home"] .nav-links a,
body[data-page="home"] .nav-menu summary,
body[data-page="home"] .nav-login-button {
  color: var(--muted);
  white-space: nowrap;
}

body[data-page="home"] .nav-links a:hover,
body[data-page="home"] .nav-links a:focus-visible,
body[data-page="home"] .nav-menu summary:hover,
body[data-page="home"] .nav-menu summary:focus-visible,
body[data-page="home"] .nav-login-button:hover,
body[data-page="home"] .nav-login-button:focus-visible,
body[data-page="home"] .nav-links a.active,
body[data-page="home"] .nav-menu.active summary,
body[data-page="home"] .nav-menu[open] summary {
  color: var(--brand);
  background: rgba(184, 78, 48, 0.09);
}

body[data-page="home"] .nav-menu-panel {
  background: rgba(255, 255, 255, 0.97);
  border-color: rgba(17, 24, 39, 0.1);
  box-shadow: 0 18px 42px rgba(17, 24, 39, 0.14);
}

body[data-page="home"] .nav-menu-panel a {
  color: var(--ink-2);
}

body[data-page="home"] .nav-menu-panel a:hover,
body[data-page="home"] .nav-menu-panel a:focus-visible,
body[data-page="home"] .nav-menu-panel a.active {
  color: var(--brand);
  background: rgba(184, 78, 48, 0.09);
}

body[data-page="home"] .nav-toggle {
  color: var(--ink);
  border-color: rgba(17, 24, 39, 0.14);
  background: rgba(255, 255, 255, 0.74);
}

@media (max-width: 760px) {
  body[data-page="home"] .nav-links {
    background: rgba(255, 255, 255, 0.97);
    border-color: rgba(17, 24, 39, 0.1);
  }

  body[data-page="home"] .nav-menu-panel {
    background: rgba(184, 78, 48, 0.04);
    border-color: rgba(184, 78, 48, 0.1);
  }
}

.splash {
  position: relative;
  min-height: calc(100vh - 58px);
  min-height: calc(100dvh - 58px);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: 2rem 1.5rem;
  background: var(--paper);
}

body[data-page="home"] .splash {
  background: var(--paper);
  min-height: 100vh;
  min-height: 100dvh;
}

.splash-media,
.splash-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

body[data-page="home"] .splash-media {
  opacity: 1;
}

.splash-glow {
  display: none;
}

.splash-content {
  position: relative;
  display: grid;
  justify-items: center;
  text-align: center;
  gap: 1.4rem;
  width: min(44rem, 100%);
  animation: splash-rise 0.9s var(--ease, ease) both;
}

.splash-logo {
  width: 92px;
  height: 92px;
  border-radius: 50%;
  box-shadow: var(--shadow-md);
}

body[data-page="home"] .splash-logo {
  display: block;
}

.splash-title {
  margin: 0;
  font-family: var(--font-display, "Outfit", sans-serif);
  font-size: clamp(2.3rem, 9vw, 5.6rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  line-height: 1.05;
  max-width: 100%;
  color: var(--brand);
}

body[data-page="home"] .splash-title {
  color: var(--brand);
}

.splash-copy {
  margin: 0;
  max-width: min(34rem, 100%);
  color: var(--muted);
  font-size: clamp(1rem, 2.4vw, 1.18rem);
  line-height: 1.65;
}

body[data-page="home"] .splash-copy {
  color: var(--muted);
}

.splash-button {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  margin-top: 0.6rem;
  padding: 1.05rem 2.9rem;
  border-radius: 999px;
  background: var(--brand);
  color: #ffffff;
  font-family: var(--font-display, "Outfit", sans-serif);
  font-size: 1.02rem;
  font-weight: 700;
  letter-spacing: 0.22em;
  text-decoration: none;
  box-shadow: var(--shadow-brand);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

body[data-page="home"] .splash-button {
  background: var(--brand);
  color: #ffffff;
  letter-spacing: 0.22em;
  font-size: 1.02rem;
  box-shadow: var(--shadow-brand);
}

.splash-button svg {
  width: 1.15rem;
  height: 1.15rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.4;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform 0.25s ease;
}

.splash-button:hover,
.splash-button:focus-visible {
  transform: translateY(-2px);
  box-shadow: var(--shadow-brand-lg);
}

body[data-page="home"] .splash-button:hover,
body[data-page="home"] .splash-button:focus-visible {
  box-shadow: var(--shadow-brand-lg);
}

.splash-button:hover svg,
.splash-button:focus-visible svg {
  transform: translateX(4px);
}

.splash-foot {
  position: absolute;
  bottom: 1.4rem;
  left: 0;
  right: 0;
  margin: 0;
  text-align: center;
  font-size: 0.82rem;
  color: var(--muted);
}

body[data-page="home"] .splash-foot {
  color: var(--muted);
}

.splash-foot a {
  color: var(--brand);
  text-decoration: none;
}

.splash-foot a:hover {
  text-decoration: underline;
}

.home-main {
  background:
    linear-gradient(180deg, var(--paper) 0, var(--paper) 42rem, var(--surface-2) 42rem),
    var(--paper);
}


@keyframes splash-rise {
  from {
    opacity: 0;
    transform: translateY(18px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-reduced-motion: reduce) {
  .splash-content {
    animation: none;
  }
}

@media (max-width: 900px) {


}

@media (max-width: 640px) {


}

/* ------------------------------ theory problems ---------------------------- */
/* Reads like an exam paper: a narrow measure, numbered parts with point values
   in the margin language of the official PDFs, and a per-part solution panel
   that stays shut until the student asks for it. */

.theory-paper {
  width: min(100%, 820px);
  margin: 0 auto;
  padding: 0 0 3rem;
}

.theory-back {
  display: inline-block;
  margin-bottom: 1.2rem;
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 700;
  text-decoration: none;
}

.theory-back:hover {
  color: var(--brand);
}

.theory-kicker {
  margin: 0;
  color: var(--brand);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.theory-head h1 {
  margin: 0.45rem 0 0;
  color: var(--brand);
  font-size: clamp(1.6rem, 3.6vw, 2.3rem);
  letter-spacing: -0.02em;
  line-height: 1.15;
}

.theory-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.9rem;
}

.theory-meta-chip {
  padding: 0.2rem 0.6rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 700;
}

.theory-meta-link {
  color: var(--brand);
  font-size: 0.8rem;
  font-weight: 700;
}

.theory-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 1.2rem;
  padding-bottom: 1.4rem;
  border-bottom: 1px solid var(--line);
}

.theory-overview {
  margin-top: 1.6rem;
  color: var(--ink-2);
  font-size: 1rem;
  line-height: 1.7;
}

.theory-overview p {
  margin: 0 0 0.9rem;
}

.theory-setup {
  margin-top: 1.2rem;
  padding: 1.1rem 1.3rem;
  border: 1px solid var(--line-soft);
  border-left: 3px solid var(--brand);
  border-radius: var(--radius);
  background: var(--surface-2);
}

.theory-setup p:last-child {
  margin-bottom: 0;
}

.theory-part {
  margin-top: 2.2rem;
  padding-top: 1.6rem;
  border-top: 1px solid var(--line-soft);
}

.theory-part:first-child {
  border-top: 0;
}

.theory-part-head {
  margin: 0 0 0.9rem;
  font-size: 1.08rem;
  letter-spacing: -0.01em;
}

.theory-part-body {
  color: var(--ink-2);
  font-size: 0.97rem;
  line-height: 1.7;
}

.theory-part-body p,
.theory-answer p {
  margin: 0 0 0.8rem;
}

.theory-list,
.theory-choices {
  margin: 0 0 0.9rem;
  padding-left: 1.2rem;
  line-height: 1.65;
}

/* Choices are already labelled "A." ... "E." in the content, matching the
   official papers, so the list itself carries no marker. */
.theory-choices {
  list-style: none;
  padding-left: 0;
  display: grid;
  gap: 0.35rem;
}

.theory-choices li {
  padding: 0.45rem 0.75rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  font-size: 0.94rem;
}

.theory-tex {
  overflow-x: auto;
  overflow-y: hidden;
  margin: 0.4rem 0 1rem;
  padding: 0.2rem 0;
}

/* Inline math sits in running prose, outside the .theory-tex scroller, so a
   long expression would otherwise drag the whole page sideways on mobile. */
.theory-part-body .katex,
.theory-answer .katex,
.theory-overview .katex,
.mock-body .katex {
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  vertical-align: middle;
}

.theory-tex-note {
  margin: -0.5rem 0 0.9rem;
  color: var(--muted);
  font-size: 0.85rem;
}

.theory-tex-fallback {
  margin: 0;
  padding: 0.7rem 0.9rem;
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  white-space: pre-wrap;
}

.theory-code {
  margin: 0.5rem 0 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--code-bg);
}

.theory-code-head {
  padding: 0.35rem 0.8rem;
  border-bottom: 1px solid var(--line-soft);
  background: var(--paper);
  color: var(--muted-2);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.theory-code pre {
  margin: 0;
  padding: 0.8rem 0.9rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.55;
  color: var(--ink-2);
}

.theory-requirement {
  margin: 0.2rem 0 0;
  color: var(--clay);
  font-size: 0.86rem;
  font-style: italic;
  font-weight: 600;
}

.theory-reveal {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  margin-top: 0.9rem;
  padding: 0.5rem 0.95rem;
  border: 1px solid var(--brand);
  border-radius: 999px;
  background: var(--brand-soft);
  color: var(--brand-strong);
  font-family: inherit;
  font-size: 0.84rem;
  font-weight: 700;
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.theory-reveal svg {
  width: 15px;
  height: 15px;
  flex: none;
}

.theory-reveal:hover,
.theory-reveal:focus-visible {
  background: var(--paper);
  outline: none;
}

.theory-reveal.revealed {
  border-color: var(--line);
  background: var(--surface-2);
  color: var(--muted);
}

.theory-answer {
  margin-top: 1rem;
  padding: 1.1rem 1.3rem;
  border: 1px solid var(--line-soft);
  border-left: 3px solid var(--green);
  border-radius: var(--radius);
  background: var(--surface-2);
  font-size: 0.95rem;
  line-height: 1.7;
  animation: theory-answer-in var(--t-mid) var(--ease);
}

@keyframes theory-answer-in {
  from {
    opacity: 0;
    transform: translateY(-4px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

.theory-answer-label {
  margin: 0 0 0.7rem !important;
  color: var(--green);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.theory-answer .theory-code,
.theory-answer .theory-choices li {
  background: var(--paper);
}

.theory-result {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  margin: 0.9rem 0 0 !important;
  padding: 0.6rem 0.85rem;
  border-radius: var(--radius-sm);
  background: var(--green-soft);
  font-weight: 700;
}

.theory-result span {
  color: var(--green);
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  white-space: nowrap;
}

.theory-footnote {
  margin: 2.6rem 0 0;
  padding-top: 1.4rem;
  border-top: 1px solid var(--line-soft);
  color: var(--muted);
  font-size: 0.85rem;
  line-height: 1.6;
}

@media (max-width: 640px) {
  .theory-toolbar .button {
    width: 100%;
    justify-content: center;
  }

  .theory-answer,
  .theory-setup {
    padding: 0.9rem 1rem;
  }
}

/* -------------------------------- mock arena ------------------------------- */
/* Self-built timed mock: a setup form (duration + search + chosen set), then a
   running view dominated by the clock, then a summary. */

.mock-block {
  margin-top: 1.4rem;
}

.mock-label {
  display: block;
  margin: 0 0 0.5rem;
  color: var(--ink-2);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.mock-label.subtle {
  margin-top: 1.1rem;
  color: var(--muted-2);
  font-weight: 700;
}

.mock-duration {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.mock-minutes {
  width: 6rem;
  padding: 0.55rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  color: var(--ink);
  font-family: inherit;
  font-size: 1.05rem;
  font-weight: 700;
}

.mock-minutes:focus-visible {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 3px var(--brand-ring);
}

.mock-unit {
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 600;
}

.mock-quick-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-left: auto;
}

.mock-quick {
  padding: 0.4rem 0.7rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 700;
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.mock-quick:hover {
  border-color: var(--brand);
  color: var(--brand);
}

.mock-quick.active {
  border-color: var(--brand);
  background: var(--brand-soft);
  color: var(--brand-strong);
}

.mock-search {
  width: 100%;
  margin-bottom: 0.6rem;
}

.mock-results,
.mock-chosen-list,
.mock-run-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0.4rem;
}

.mock-result {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  width: 100%;
  padding: 0.6rem 0.8rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--surface-2);
  font-family: inherit;
  text-align: left;
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.mock-result:hover,
.mock-result:focus-visible {
  border-color: var(--brand);
  background: var(--brand-soft);
  outline: none;
}

.mock-result-copy,
.mock-chosen-copy,
.mock-run-copy {
  display: grid;
  gap: 0.15rem;
  min-width: 0;
  flex: 1;
}

.mock-result-copy strong,
.mock-chosen-copy strong,
.mock-run-copy strong {
  color: var(--ink);
  font-size: 0.92rem;
  line-height: 1.35;
}

.mock-result-copy small,
.mock-chosen-copy small,
.mock-run-copy small {
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 600;
}

.mock-result-add {
  flex: none;
  display: grid;
  place-items: center;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--brand-soft);
  color: var(--brand-strong);
  font-size: 1rem;
  font-weight: 800;
  line-height: 1;
}

.mock-generators {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.mock-generator {
  display: grid;
  gap: 0.1rem;
  padding: 0.5rem 0.8rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  color: var(--ink-2);
  font-family: inherit;
  font-size: 0.86rem;
  font-weight: 700;
  text-align: left;
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease);
}

.mock-generator small {
  color: var(--muted-2);
  font-size: 0.72rem;
  font-weight: 600;
}

.mock-generator:hover:not([disabled]) {
  border-color: var(--brand);
}

.mock-generator[disabled] {
  opacity: 0.45;
  cursor: not-allowed;
}

.mock-hint {
  margin-top: 0.5rem;
}

.mock-chosen-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.6rem;
}

.mock-count {
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 700;
}

.mock-chosen {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  padding: 0.55rem 0.7rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--paper);
}

.mock-chosen-index {
  flex: none;
  display: grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--fill-shape);
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
}

.mock-remove {
  flex: none;
  width: 24px;
  height: 24px;
  border: 0;
  border-radius: 50%;
  background: none;
  color: var(--muted-2);
  font-size: 1.1rem;
  line-height: 1;
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.mock-remove:hover {
  background: var(--coral-soft);
  color: var(--coral);
}

.mock-empty {
  padding: 0.7rem 0.2rem;
  color: var(--muted);
  font-size: 0.88rem;
}

.mock-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.5rem;
}

.mock-actions .button[disabled] {
  opacity: 0.45;
  cursor: not-allowed;
}

/* running */

.mock-timer-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding: 1.2rem 1.4rem;
  border: 1px solid var(--line);
  border-left: 4px solid var(--brand);
  border-radius: var(--radius-lg);
  background: var(--surface-2);
}

.mock-timer-card.expired {
  border-left-color: var(--coral);
  background: var(--coral-soft);
}

.mock-timer-label {
  margin: 0;
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.mock-timer {
  margin: 0.2rem 0 0;
  font-family: var(--font-mono);
  font-size: clamp(2rem, 6vw, 3rem);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
}

.mock-timer-card.expired .mock-timer {
  color: var(--coral);
}

.mock-timer-side {
  display: grid;
  gap: 0.5rem;
  justify-items: end;
}

.mock-progress {
  margin: 0;
  color: var(--muted);
  font-size: 0.88rem;
}

.mock-progress strong {
  color: var(--ink);
  font-size: 1.05rem;
}

.mock-run-list {
  margin-top: 1rem;
}

.mock-run-row {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  padding: 0.7rem 0.85rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--paper);
}

.mock-run-row.done .mock-run-copy strong {
  color: var(--muted-2);
  text-decoration: line-through;
}

.mock-run-check input {
  width: 18px;
  height: 18px;
  cursor: pointer;
  accent-color: var(--green);
}

.mock-open {
  flex: none;
  color: var(--brand);
  font-size: 0.84rem;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}

.mock-open:hover {
  text-decoration: underline;
}

/* Statement / Code tab and the download, sitting beside "Mark as done". */
.mock-viewtab,
.mock-download {
  padding: 0.45rem 0.9rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  font-family: inherit;
  font-size: 0.84rem;
  font-weight: 700;
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.mock-viewtab:hover,
.mock-download:hover {
  border-color: var(--brand);
  color: var(--brand);
}

.mock-viewtab.active {
  border-color: var(--brand);
  background: var(--brand-soft);
  color: var(--brand-strong);
}

/* The built-in IDE, framed as a tab of the mock paper. */
.mock-ide {
  display: block;
  width: 100%;
  height: min(78vh, 900px);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
}

/* editor/?embed=1 — chromeless, for framing inside the Mock Arena. */
body.editor-embed .site-header,
body.editor-embed .site-footer,
body.editor-embed .page-hero,
body.editor-embed .skip-link,
body.editor-embed .editor-note {
  display: none;
}

body.editor-embed main#main,
body.editor-embed .page-shell {
  padding: 0;
  margin: 0;
  width: 100%;
  max-width: none;
}

body.editor-embed .editor-panel {
  border: 0;
  border-radius: 0;
  padding: 0;
  gap: 0;
}

/* The toolbar's sticky offset clears the site header, which embed mode hides —
   left as-is it floats 76px down, leaving dead space and overlapping cell 1. */
body.editor-embed .editor-toolbar {
  top: 0;
  border-width: 0 0 1px;
  border-radius: 0;
  padding: 8px 12px;
  box-shadow: none;
}

body.editor-embed .editor-cells {
  padding: 0.6rem 0.75rem 1rem;
}

/* summary */

.mock-summary {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 0.6rem;
  margin: 1rem 0;
}

.mock-stat {
  display: grid;
  gap: 0.2rem;
  padding: 0.8rem 0.9rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--surface-2);
}

.mock-stat span {
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.mock-stat strong {
  color: var(--ink);
  font-size: 1.3rem;
}

@media (max-width: 640px) {
  .mock-quick-row {
    margin-left: 0;
  }

  .mock-timer-side {
    justify-items: start;
  }
}

/* ----------------------------- mock arena: run ----------------------------- */
/* The sitting itself: a sticky clock bar, a problem switcher down the side, and
   one statement at a time. No solutions are rendered anywhere in this view. */

.mock-setup-shell {
  width: min(100%, 780px);
  margin: 0 auto;
}

.mock-run-shell {
  width: min(100%, 1180px);
  margin: 0 auto;
}

.mock-bar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding: 0.9rem 1.2rem;
  border: 1px solid var(--line);
  border-left: 4px solid var(--brand);
  border-radius: var(--radius-lg);
  background: var(--paper);
  box-shadow: var(--shadow-sm);
}

.mock-bar.expired {
  border-left-color: var(--coral);
  background: var(--coral-soft);
}

.mock-bar-time {
  display: flex;
  align-items: baseline;
  gap: 0.7rem;
}

.mock-bar-label {
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.mock-bar .mock-timer {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(1.6rem, 4vw, 2.2rem);
  font-weight: 600;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.mock-bar.expired .mock-timer {
  color: var(--coral);
}

.mock-bar-side {
  display: flex;
  align-items: center;
  gap: 0.8rem;
}

.mock-run-layout {
  display: grid;
  grid-template-columns: minmax(220px, 280px) minmax(0, 1fr);
  gap: 1.2rem;
  margin-top: 1.2rem;
  align-items: start;
}

@media (max-width: 900px) {
  .mock-run-layout {
    grid-template-columns: 1fr;
  }
}

.mock-switcher {
  position: sticky;
  top: 6.5rem;
  display: grid;
  gap: 0.35rem;
  padding: 0.6rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--panel);
}

@media (max-width: 900px) {
  .mock-switcher {
    position: static;
    grid-auto-flow: column;
    grid-auto-columns: minmax(190px, 1fr);
    overflow-x: auto;
  }
}

.mock-tab {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.55rem 0.6rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  background: none;
  font-family: inherit;
  text-align: left;
  cursor: pointer;
  transition: background var(--t-fast) var(--ease), border-color var(--t-fast) var(--ease);
}

.mock-tab:hover {
  background: var(--surface-2);
}

.mock-tab.active {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.mock-tab-num {
  flex: none;
  display: grid;
  place-items: center;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--fill-shape);
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 800;
}

.mock-tab.done .mock-tab-num {
  background: var(--green);
  color: #fff;
}

.mock-tab-copy {
  display: grid;
  gap: 0.1rem;
  min-width: 0;
}

.mock-tab-copy strong {
  color: var(--ink);
  font-size: 0.86rem;
  line-height: 1.3;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.mock-tab-copy small {
  color: var(--muted-2);
  font-size: 0.72rem;
  font-weight: 600;
}

.mock-tab.done .mock-tab-copy strong {
  color: var(--muted-2);
  text-decoration: line-through;
}

.mock-paper {
  padding: 1.6rem 1.8rem 1.8rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--paper);
  min-width: 0;
}

.mock-paper-kicker {
  margin: 0;
  color: var(--brand);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.mock-paper-head h2 {
  margin: 0.4rem 0 0;
  font-size: clamp(1.3rem, 3vw, 1.8rem);
  letter-spacing: -0.02em;
}

.mock-paper-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.6rem;
  margin: 1rem 0 0;
  padding-bottom: 1.2rem;
  border-bottom: 1px solid var(--line-soft);
}

.mock-mark {
  padding: 0.45rem 0.9rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  font-family: inherit;
  font-size: 0.84rem;
  font-weight: 700;
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease), background var(--t-fast) var(--ease);
}

.mock-mark:hover {
  border-color: var(--green);
  color: var(--green);
}

.mock-mark.done {
  border-color: var(--green);
  background: var(--green-soft);
  color: var(--green);
}

.mock-body {
  margin-top: 1.3rem;
  color: var(--ink-2);
  font-size: 0.97rem;
  line-height: 1.7;
}

.mock-body p {
  margin: 0 0 0.9rem;
}

.mock-body h2,
.mock-body h3,
.mock-body h4,
.mock-body h5 {
  margin: 1.5rem 0 0.6rem;
  letter-spacing: -0.01em;
}

.mock-loading {
  color: var(--muted);
  font-style: italic;
}

.mock-part {
  margin-top: 1.6rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line-soft);
}

.mock-part h3 {
  margin: 0 0 0.7rem;
  font-size: 1.05rem;
}

.mock-pager {
  display: flex;
  justify-content: space-between;
  gap: 0.6rem;
  margin-top: 2rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line-soft);
}

.mock-pager .button[disabled] {
  opacity: 0.4;
  cursor: not-allowed;
}

/* review / summary */

.mock-review-list {
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 0.45rem;
}

.mock-review-row {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  padding: 0.75rem 0.9rem;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background: var(--surface-2);
}

.mock-review-mark {
  flex: none;
  display: grid;
  place-items: center;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--fill-shape);
  color: var(--muted);
  font-weight: 800;
}

.mock-review-row.done .mock-review-mark {
  background: var(--green-soft);
  color: var(--green);
}

.mock-solution-link {
  flex: none;
  color: var(--brand);
  font-size: 0.85rem;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}

.mock-solution-link:hover {
  text-decoration: underline;
}

@media (max-width: 640px) {
  .mock-paper {
    padding: 1.1rem 1.1rem 1.3rem;
  }

  .mock-review-row {
    flex-wrap: wrap;
  }
}

/* --------------------- mock arena: full-screen a problem ------------------- */

.mock-paper-head {
  position: relative;
}

.mock-fullscreen {
  position: absolute;
  top: 0;
  right: 0;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.7rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  font-family: inherit;
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
  transition: border-color var(--t-fast) var(--ease), color var(--t-fast) var(--ease);
}

.mock-fullscreen svg {
  width: 13px;
  height: 13px;
  flex: none;
}

.mock-fullscreen:hover {
  border-color: var(--brand);
  color: var(--brand);
}

/* Expanded layout. Driven by a class on the shell (which survives re-render)
   rather than by :fullscreen on an element render() would destroy. */
.mock-run-shell.mock-fs {
  --mock-fs-gutter: clamp(0.5rem, 2vw, 2rem);
  position: fixed;
  inset: 0;
  z-index: 60;
  width: 100%;
  max-width: none;
  margin: 0;
  padding: 0.9rem var(--mock-fs-gutter) 1.5rem;
  overflow-y: auto;
  background: var(--paper);
}

/* Let the IDE run edge to edge: cancel the shell gutter too. */
.mock-run-shell.mock-fs .mock-run-layout:has(.mock-body.is-code) {
  margin-left: calc(-1 * var(--mock-fs-gutter));
  margin-right: calc(-1 * var(--mock-fs-gutter));
}

body.mock-fs-active {
  overflow: hidden;
}

body.mock-fs-active .site-header {
  display: none;
}

/* One problem, full width — the sidebar switcher gives way to the pager. */
.mock-run-shell.mock-fs .mock-switcher {
  display: none;
}

.mock-run-shell.mock-fs .mock-run-layout {
  grid-template-columns: minmax(0, 1fr);
}

.mock-run-shell.mock-fs .mock-paper {
  border: 0;
  padding: 1.4rem var(--mock-fs-gutter) 1rem;
}

/* Prose keeps a readable measure; the IDE does not — it bleeds back out
   through the paper's gutter so it spans the full width of the screen. */
.mock-run-shell.mock-fs .mock-body {
  max-width: 1000px;
}

.mock-run-shell.mock-fs .mock-body.is-code {
  max-width: none;
  margin-left: calc(-1 * var(--mock-fs-gutter));
  margin-right: calc(-1 * var(--mock-fs-gutter));
}

.mock-run-shell.mock-fs .mock-ide {
  height: calc(100vh - 250px);
  min-height: 460px;
}

.mock-run-shell.mock-fs .mock-body.is-code .mock-ide {
  border-left: 0;
  border-right: 0;
  border-radius: 0;
}

.mock-fullscreen[aria-pressed="true"] {
  border-color: var(--brand);
  background: var(--brand-soft);
  color: var(--brand-strong);
}

@media (max-width: 640px) {
  .mock-fullscreen span {
    display: none;
  }
}
/* OAuth providers */
.auth-modal-actions {
  display: grid;
  gap: 10px;
}

.auth-provider-button {
  justify-content: center;
}

.auth-provider-mark--google {
  display: inline-grid;
  width: 18px;
  height: 18px;
  place-items: center;
  border: 1px solid currentColor;
  border-radius: 50%;
  font-family: var(--font-body);
  font-size: 11px;
  font-weight: 800;
}


/* --- module reader typography ----------------------------------------------
   Mirrors usaco.guide's `.markdown` scale so a module reads the same way:
   Inter at 1rem/1.5, 1.875rem bold section headings in gray-700, 1.5rem
   semibold sub-headings, blue-600 semibold links, and Tailwind's 0.25rem
   spacing step throughout. Scoped to .reader-article so the surrounding site
   chrome keeps its own Outfit-based styling. */

.reader-article {
  font-family: var(--font-reader);
  font-size: 1rem;
  line-height: 1.5;
  color: var(--reader-ink);
  overflow-wrap: break-word;
  -webkit-font-smoothing: antialiased;
}

.reader-article .reader-head h1 {
  font-family: var(--font-reader);
  font-size: 1.875rem;
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: 0;
  color: var(--reader-ink-strong);
}

/* Section heading — usaco.guide: mt-12 mb-5 text-3xl leading-tight font-bold. */
.reader-article .reader-section h2.reader-section-label {
  font-family: var(--font-reader);
  margin: 3rem 0 1.25rem;
  font-size: 1.875rem;
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: none;
  color: var(--reader-ink);
}

/* Sub-heading — usaco.guide: mt-8 mb-4 text-2xl leading-snug font-semibold. */
.reader-article h3.reader-subhead {
  font-family: var(--font-reader);
  margin: 2rem 0 1rem;
  font-size: 1.5rem;
  line-height: 1.375;
  font-weight: 600;
  letter-spacing: 0;
  color: var(--reader-ink);
}

.reader-article h4.reader-subhead {
  font-family: var(--font-reader);
  margin: 1.5rem 0 1rem;
  font-size: 1.125rem;
  line-height: 1.5;
  font-weight: 600;
  letter-spacing: 0;
  color: var(--reader-ink);
}

.reader-article .reader-section > .reader-subhead:first-of-type {
  margin-top: 1rem;
}

.reader-article p {
  margin: 0 0 1rem;
  font-size: 1rem;
  line-height: 1.5;
  color: var(--reader-ink);
}

.reader-article a {
  color: var(--reader-link);
  font-weight: 600;
  text-decoration: none;
}

.reader-article a:hover {
  text-decoration: underline;
}

.reader-article ul.reader-block-list,
.reader-article ol.reader-block-list {
  display: block;
  margin: 0 0 1.5rem;
  font-size: 1rem;
  line-height: 1.5;
}

.reader-article ul.reader-block-list {
  list-style-type: disc;
  padding-left: 2rem;
}

.reader-article ol.reader-block-list {
  padding-left: 1.25rem;
}

.reader-article ul.reader-block-list > li,
.reader-article ol.reader-block-list > li {
  margin-bottom: 0.5rem;
  color: var(--reader-ink);
}

.reader-article ul.reader-block-list > li:last-child,
.reader-article ol.reader-block-list > li:last-child {
  margin-bottom: 0;
}

.reader-article ol.reader-block-list > li::marker {
  color: var(--reader-link);
  font-weight: 600;
}

.reader-article ul.reader-block-list > li::marker {
  color: var(--reader-ink);
}

.reader-article blockquote.reader-quote {
  margin: 0 0 1rem;
  padding: 0 1rem;
  border-left: 4px solid var(--reader-rule);
  border-radius: 0;
  background: none;
  font-size: 1rem;
  line-height: 1.5;
  color: var(--reader-ink-soft);
}

.reader-article blockquote.reader-quote p {
  color: inherit;
}

.reader-article blockquote.reader-quote p:last-child {
  margin-bottom: 0;
}

.reader-article :not(pre) > code {
  padding: 0.125rem 0.25rem;
  border-radius: 0.25rem;
  background: var(--reader-code-bg);
  font-family: var(--font-mono);
  font-size: 0.875rem;
}

.reader-article .reader-code-block,
.reader-article pre {
  margin: 1rem 0;
  font-size: 0.875rem;
}

.reader-article table {
  font-size: 1rem;
  line-height: 1.5;
  border-collapse: collapse;
}

.reader-article table th,
.reader-article table td {
  padding: 0.25rem 0.75rem;
  border: 1px solid var(--reader-rule);
}


/* --- module header, matched to usaco.guide -------------------------------
   Values taken from the live page's Tailwind classes: the level/progress row
   is `mb-4 flex justify-between`, the title row `mb-4 sm:flex` with an
   `text-3xl font-bold text-gray-900` heading and a bordered status button,
   the description `mb-4 italic`, and the prerequisites panel
   `mb-4 rounded-md bg-gray-50 p-6`. */

.reader-article .reader-progress-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1rem;
}

.reader-article .reader-level {
  font-size: 1rem;
  font-weight: 500;
  color: #c2410c; /* orange-700, where the frequency label sits */
}

.reader-article .reader-progress {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.reader-article .reader-progress-track {
  display: block;
  width: 6rem;
  height: 0.5rem;
  overflow: hidden;
  border-radius: 999px;
  background: #e5e7eb;
}

.reader-article .reader-progress-fill {
  display: block;
  height: 0.5rem;
  background: #22c55e;
}

.reader-article .reader-progress-count {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--reader-ink);
}

.reader-article .reader-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin: 0 0 1rem;
  padding: 0;
  border: 0;
}

.reader-article .reader-head-main {
  min-width: 0;
  flex: 1;
}

.reader-article .reader-head h1 {
  margin: 0;
  font-family: var(--font-reader);
  font-size: 1.875rem;
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: 0;
  color: var(--reader-ink-strong);
}

.reader-article .reader-head-status {
  flex-shrink: 0;
  margin-left: 1rem;
}

.reader-article .reader-status-select {
  appearance: none;
  padding: 0.5rem 2rem 0.5rem 1rem;
  border: 1px solid var(--reader-rule);
  border-radius: 0.375rem;
  background-color: #fff;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='%23374151'%3E%3Cpath d='M12.53 16.28a.75.75 0 0 1-1.06 0l-7.5-7.5a.75.75 0 0 1 1.06-1.06L12 14.69l6.97-6.97a.75.75 0 1 1 1.06 1.06l-7.5 7.5Z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.5rem center;
  background-size: 1.15rem;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
  font-family: var(--font-reader);
  font-size: 0.875rem;
  line-height: 1.25rem;
  font-weight: 500;
  color: var(--reader-ink);
  cursor: pointer;
}

.reader-article .reader-status-select:hover {
  color: #6b7280;
}

.reader-article .reader-status-login {
  min-height: 2.25rem;
  padding: 0.5rem 1rem;
  border: 1px solid var(--reader-rule);
  border-radius: 0.375rem;
  background: #fff;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
  color: var(--reader-link);
  cursor: pointer;
  font-family: var(--font-reader);
  font-size: 0.875rem;
  line-height: 1.25rem;
  font-weight: 600;
}

.reader-article .reader-status-login:hover,
.reader-article .reader-status-login:focus-visible {
  color: #6b7280;
  outline: none;
}

@media (max-width: 720px) {
  .reader-article .reader-head {
    align-items: flex-start;
    flex-direction: column;
  }

  .reader-article .reader-head-status {
    margin-left: 0;
  }
}

.reader-article .reader-lede {
  margin: 0 0 1rem;
  font-size: 1rem;
  line-height: 1.5;
  font-style: italic;
  color: var(--reader-ink);
}

.reader-article .reader-infocard {
  margin: 0 0 1rem;
  padding: 1.5rem;
  border: 0;
  border-radius: 0.375rem;
  background: #f9fafb;
}

.reader-article .reader-infocard h2 {
  margin: 0 0 0.5rem;
  font-family: var(--font-reader);
  font-size: 1rem;
  line-height: 1.5;
  font-weight: 400;
  letter-spacing: 0;
  text-transform: none;
  color: var(--reader-ink);
}

.reader-article .reader-prereq-list {
  margin: 0;
  padding-left: 2rem;
  list-style: disc;
}

.reader-article .reader-prereq-list li {
  margin-bottom: 0.25rem;
  font-size: 1rem;
  line-height: 1.5;
}

.reader-article .reader-prereq-list a {
  font-weight: 400;
  color: var(--reader-ink);
  text-decoration: underline;
}

.reader-article .reader-prereq-list a:hover {
  color: var(--reader-link);
}

/* Prev · breadcrumb · Next reads in gray on the reference, not brand blue. */
.reader-article .reader-topbar {
  margin-bottom: 2rem;
}

.reader-article .reader-topbar a,
.reader-article .reader-crumbs a {
  font-size: 1rem;
  font-weight: 400;
  color: #4b5563;
}

.reader-article .reader-topbar a:hover,
.reader-article .reader-crumbs a:hover {
  color: var(--reader-ink-strong);
  text-decoration: none;
}

.reader-article .reader-crumbs [aria-current="page"] {
  font-weight: 400;
  color: var(--reader-ink-strong);
}

/* --- sidebar, matched to usaco.guide -------------------------------------
   Chapter headers are `px-4 py-3 text-sm leading-5 font-semibold text-gray-800`
   with a gray-200 divider; module links are `py-3 pr-4 pl-12 text-sm leading-5`
   and the active one turns blue on a #f7faff group. */

.reader-sidenav {
  font-family: var(--font-reader);
  background: #fff;
  border-right-color: #e5e7eb;
}

.reader-sidenav .reader-stage summary {
  justify-content: center;
  padding: 1rem 0;
  font-size: 1rem;
  line-height: 1.5rem;
  font-weight: 500;
  color: var(--reader-ink-strong);
}

.reader-sidenav .reader-chapter {
  border-bottom: 1px solid #e5e7eb;
}

.reader-sidenav .reader-chapter.active {
  background: #f7faff;
}

.reader-sidenav .reader-chapter > summary {
  padding: 0.75rem 1rem;
  font-size: 0.875rem;
  line-height: 1.25rem;
  font-weight: 600;
  color: #1f2937;
}

.reader-sidenav .reader-chapter ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

.reader-sidenav .reader-chapter ol a {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem 0.75rem 3rem;
  font-size: 0.875rem;
  line-height: 1.25rem;
  font-weight: 400;
  color: var(--reader-ink);
}

.reader-sidenav .reader-chapter ol a:hover {
  background: #eff6ff;
}

.reader-sidenav .reader-chapter ol a.active {
  font-weight: 500;
  color: var(--reader-link);
}

.reader-sidenav .reader-nav-footer a {
  font-family: var(--font-reader);
  font-size: 0.875rem;
  line-height: 1.25rem;
  font-weight: 400;
}

/* The dot sits on the rail to the left of the pl-12 text column, and turns
   blue with the active link the way the reference does. */
.reader-sidenav .reader-nav-dot {
  left: 1.75rem;
}

.reader-sidenav .reader-chapter a.active .reader-nav-dot {
  background: var(--reader-link);
}

/* Rail follows the sidebar's pl-12 text column and keeps the reference's
   neutral tone; only the dot marks the active module. */
.reader-sidenav .reader-chapter li::before {
  left: 1.75rem;
}

.reader-sidenav .reader-chapter li.active::before {
  left: 1.7rem;
  width: 3px;
  background: var(--reader-link);
}

/* --- top-of-page rhythm, matched to usaco.guide ---------------------------
   Their header is: topbar, a single `h-8` (2rem) spacer, then the level and
   progress row. The old rule paired a 1.9rem padding with a 2rem margin, which
   stacked into roughly double the reference gap. */
.reader-article .reader-topbar {
  padding-bottom: 0;
  margin-bottom: 2rem;
}

.reader-article {
  padding-top: 1.75rem;
}

/* Sidebar is 320px on the reference at this width, not 355px. */
.usaco-reader {
  grid-template-columns: 320px minmax(2rem, 0.55fr) minmax(0, 896px) minmax(2rem, 1.45fr);
}

/* Logo row is `pt-5 px-4 pb-2`; the stage selector is a centered
   `text-base leading-6 font-medium` button with `my-4`. */
.reader-sidenav .reader-nav-top {
  padding: 1.25rem 1rem 0.5rem;
}

.reader-sidenav .reader-stage {
  padding: 0;
  text-align: center;
  border-bottom: 1px solid #e5e7eb;
}

.reader-sidenav .reader-stage summary {
  padding: 1rem 0;
  border-radius: 0;
  font-family: var(--font-reader);
  font-size: 1rem;
  line-height: 1.5rem;
  font-weight: 500;
  letter-spacing: 0;
  color: var(--reader-ink-strong);
}

/* Code-block lines are markup as <span><b>n</b><code>…</code></span>, so the
   inline-code chip rule above would match each line and paint a second gray
   band over the block's own background. Inline chips stay; lines do not. */
.reader-article .reader-code-block code {
  padding: 0;
  border-radius: 0;
  background: none;
  font-size: inherit;
}

/* --- sidebar rail alignment ------------------------------------------------
   The dot was centred with translate(-50%) on `left`, but the rail segments
   positioned their left edge on that same value, so a 2px rail sat 1px right
   of the dot and the 3px active rail landed somewhere else again. Everything
   now centres on one axis via translateX(-50%), so the widths can differ
   without moving the centre line. */
.reader-sidenav {
  --nav-rail-x: 1.75rem;
}

.reader-sidenav .reader-nav-dot {
  left: var(--nav-rail-x);
  transform: translate(-50%, -50%);
}

.reader-sidenav .reader-chapter li::before {
  left: var(--nav-rail-x);
  width: 2px;
  transform: translateX(-50%);
}

.reader-sidenav .reader-chapter li.active::before {
  left: var(--nav-rail-x);
  width: 3px;
  transform: translateX(-50%);
  background: var(--reader-link);
}

/* --- signed-out notice ------------------------------------------------------
   Shown on the dashboard while there is no session. `updateAuthUi` toggles the
   `hidden` attribute on [data-auth-when] elements, so this and the stats panel
   swap without any page-specific script. */
.signin-notice {
  max-width: 34rem;
  margin: 4rem auto;
  padding: 2rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  text-align: center;
}

.signin-notice h1 {
  margin: 0 0 0.75rem;
  font-size: 1.5rem;
  line-height: 1.25;
  color: var(--ink);
}

.signin-notice p {
  margin: 0 0 1.5rem;
  color: var(--muted);
  line-height: 1.55;
}