/* ============================================================
   Informatique MPSI / PCSI — Manuel HTML
   Thème inspiré de discrete-mathematics.cpgeacademy.org
   Couleur principale : #026573 (teal)
   ============================================================ */

:root {
  --primary: #026573;
  --primary-dark: #014a55;
  --primary-light: #2a8c9a;
  --primary-soft: #e6f1f3;
  --primary-soft-2: #d0e4e8;
  --accent: #f59e0b;             /* gold accent for "Quick Access" / icons */

  --color-bg: #ffffff;
  --color-page: #f7faf9;
  --color-text: #1f2937;
  --color-muted: #6b7280;
  --color-rule: #e2e8eb;
  --color-link: #026573;
  --color-link-hover: #014a55;
  --color-code-bg: #f1f5f6;
  --color-code-border: #d9e2e4;
  --color-callout-bg: #f0f7f8;

  /* Encadres pedagogiques : fond / bordure / couleur du titre */
  --box-bg: #ffffff;
  --def-bg: #e6f1f3;      --def-br: #026573;   --def-fg: #014a55;
  --thm-bg: #f5f1ff;      --thm-br: #7c3aed;   --thm-fg: #6d28d9;
  --prop-bg: #eff6ff;     --prop-br: #2563eb;  --prop-fg: #1d4ed8;
  --method-bg: #ecfdf5;   --method-br: #059669; --method-fg: #047857;
  --warn-bg: #fef2f2;     --warn-br: #dc2626;  --warn-fg: #b91c1c;
  --tip-bg: #fffbeb;      --tip-br: #f59e0b;   --tip-fg: #b45309;
  --example-bg: #f8fafc;  --example-br: #64748b; --example-fg: #475569;
  --proof-bg: #fcfdfd;

  /* Difficultes des exercices */
  --d1-bg: #dcfce7; --d1-fg: #15803d;
  --d2-bg: #fef3c7; --d2-fg: #b45309;
  --d3-bg: #fee2e2; --d3-fg: #b91c1c;
  --d4-bg: #ede9fe; --d4-fg: #6d28d9;

  /* Visualisations interactives */
  --viz-bg: #fbfdfd;
  --viz-plot-bg: #ffffff;
  --viz-axis: #94a3b8;
  --viz-grid: #eef2f4;
  --viz-label: #64748b;
  --viz-ref: #cbd5e1;
  --viz-ok: #059669;
  --viz-cmp: #f59e0b;
  --viz-bad: #dc2626;
  --viz-alt: #7c3aed;
  --viz-blue: #2563eb;
  --cell-bg: #ffffff;
  --code-block-bg: #1e293b;
  --code-block-fg: #f1f5f9;

  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-serif: "Source Serif Pro", "Iowan Old Style", Georgia, serif;
  --font-mono: "JetBrains Mono", "Fira Code", "SF Mono", Consolas, monospace;

  --shadow-sm: 0 1px 3px rgba(2, 101, 115, 0.08);
  --shadow-md: 0 4px 12px rgba(2, 101, 115, 0.10);
  --shadow-lg: 0 10px 28px rgba(2, 101, 115, 0.15);

  --radius: 10px;
  --max-w: 1180px;

  color-scheme: light;
}

/* ============================================================
   THEME SOMBRE
   Active par [data-theme="dark"] sur <html>, pose par assets/theme.js
   avant le premier rendu (aucun clignotement).
   ============================================================ */

html[data-theme="dark"] {
  --primary: #3aa8b8;
  --primary-dark: #7fd3de;
  --primary-light: #2a8c9a;
  --primary-soft: #12313a;
  --primary-soft-2: #1b4552;
  --accent: #fbbf24;

  --color-bg: #111a21;
  --color-page: #0b1218;
  --color-text: #dde5ec;
  --color-muted: #93a3b1;
  --color-rule: #24333f;
  --color-link: #4fb8c8;
  --color-link-hover: #7fd3de;
  --color-code-bg: #16222b;
  --color-code-border: #273845;
  --color-callout-bg: #14242c;

  --box-bg: #16212a;
  --def-bg: #102c33;      --def-br: #3aa8b8;   --def-fg: #7fd3de;
  --thm-bg: #221c38;      --thm-br: #a78bfa;   --thm-fg: #c4b5fd;
  --prop-bg: #14243f;     --prop-br: #60a5fa;  --prop-fg: #93c5fd;
  --method-bg: #102a22;   --method-br: #34d399; --method-fg: #6ee7b7;
  --warn-bg: #2e1a1c;     --warn-br: #f87171;  --warn-fg: #fca5a5;
  --tip-bg: #2c2415;      --tip-br: #fbbf24;   --tip-fg: #fcd34d;
  --example-bg: #1a232b;  --example-br: #94a3b8; --example-fg: #cbd5e1;
  --proof-bg: #141e25;

  --d1-bg: #14361f; --d1-fg: #6ee7b7;
  --d2-bg: #3a2b12; --d2-fg: #fcd34d;
  --d3-bg: #3a1a1c; --d3-fg: #fca5a5;
  --d4-bg: #2a2145; --d4-fg: #c4b5fd;

  --viz-bg: #16212a;
  --viz-plot-bg: #0e171e;
  --viz-axis: #5a6b7a;
  --viz-grid: #1e2c36;
  --viz-label: #93a3b1;
  --viz-ref: #3c4c5a;
  --viz-ok: #34d399;
  --viz-cmp: #fbbf24;
  --viz-bad: #f87171;
  --viz-alt: #a78bfa;
  --viz-blue: #60a5fa;
  --cell-bg: #16212a;
  --code-block-bg: #0d161d;
  --code-block-fg: #dbe5ee;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 10px 28px rgba(0, 0, 0, 0.55);

  color-scheme: dark;
}

/* Bandeaux : en sombre, on garde des fonds profonds plutot que le teal clair */
html[data-theme="dark"] .site-header {
  background: #0d2830;
  border-bottom: 1px solid #1b4552;
}
html[data-theme="dark"] .hero,
html[data-theme="dark"] .lesson-hero {
  background: linear-gradient(135deg, #0d2830 0%, #071a20 100%);
}
html[data-theme="dark"] .site-footer {
  background: #0d2830;
  color: rgba(255, 255, 255, 0.8);
  border-top: 1px solid #1b4552;
}
html[data-theme="dark"] .exo-banner {
  background: #123742;
  border: 1px solid #1b4552;
}
html[data-theme="dark"] .exo-banner a {
  background: var(--primary);
  color: #06232b;
}
html[data-theme="dark"] .exo-banner a:hover { background: var(--primary-dark); }
html[data-theme="dark"] .hero .cta { background: var(--primary); color: #06232b; }
html[data-theme="dark"] .seq-card .btn.primary { color: #06232b; }
html[data-theme="dark"] .lesson-page-title .num { color: #06232b; }
html[data-theme="dark"] .keypoints {
  background: linear-gradient(135deg, var(--primary-soft) 0%, var(--color-bg) 100%);
  border-color: var(--primary-soft-2);
}
html[data-theme="dark"] .viz-controls button:hover:not(:disabled),
html[data-theme="dark"] .viz-controls button.primary { color: #06232b; }
html[data-theme="dark"] .seq-card .btn:hover { color: #06232b; }
/* MathJax suit la couleur du texte */
html[data-theme="dark"] mjx-container svg { color: var(--color-text); }

/* Transition douce lors du basculement (desactivee au chargement) */
html.theme-anime,
html.theme-anime body,
html.theme-anime .box,
html.theme-anime .exo,
html.theme-anime .viz,
html.theme-anime .cell,
html.theme-anime .seq-card,
html.theme-anime .qa-card,
html.theme-anime .lesson-content,
html.theme-anime table,
html.theme-anime th,
html.theme-anime td {
  transition: background-color 0.25s ease, color 0.25s ease,
              border-color 0.25s ease;
}

/* ============================================================
   Bouton de basculement clair / sombre
   ============================================================ */

.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  background: rgba(255, 255, 255, 0.16);
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.28);
  border-radius: 999px;
  padding: 5px 13px 5px 9px;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, transform 0.15s;
  -webkit-tap-highlight-color: transparent;
}

.theme-toggle:hover {
  background: rgba(255, 255, 255, 0.28);
  border-color: rgba(255, 255, 255, 0.5);
}
.theme-toggle:active { transform: scale(0.96); }
.theme-toggle:focus-visible {
  outline: 2px solid #fff;
  outline-offset: 2px;
}

.theme-toggle .ico {
  width: 17px;
  height: 17px;
  flex-shrink: 0;
  display: block;
}

/* icone : soleil en clair, lune en sombre */
.theme-toggle .ico-lune { display: none; }
html[data-theme="dark"] .theme-toggle .ico-soleil { display: none; }
html[data-theme="dark"] .theme-toggle .ico-lune { display: block; }

.site-header .container { position: relative; }

/* le bouton s'integre dans la barre d'en-tete, a droite */
.header-actions {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

@media (max-width: 520px) {
  .theme-toggle .lbl { display: none; }
  .theme-toggle { padding: 6px 9px; }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--color-page);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-link);
  text-decoration: none;
  transition: color 0.15s;
}
a:hover { color: var(--color-link-hover); }

img { max-width: 100%; height: auto; }

/* ============================================================
   Site Header (top bar)
   ============================================================ */

.site-header {
  background: var(--primary);
  color: #fff;
  padding: 14px 0;
  box-shadow: var(--shadow-md);
}

.site-header .container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.site-header .breadcrumb {
  font-size: 14px;
  letter-spacing: 0.04em;
  opacity: 0.92;
}

.site-header .breadcrumb a {
  color: #fff;
  border-bottom: 1px dotted rgba(255, 255, 255, 0.4);
}
.site-header .breadcrumb a:hover { border-bottom-color: #fff; }

.site-header .course-code {
  font-family: var(--font-mono);
  background: rgba(255, 255, 255, 0.15);
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 13px;
}

/* ============================================================
   Hero (index page)
   ============================================================ */

.hero {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #fff;
  padding: 70px 24px 80px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -50%;
  right: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(255,255,255,0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero .container {
  max-width: 900px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 3.2rem;
  font-weight: 700;
  margin: 0 0 12px;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.hero .subtitle {
  font-size: 1.25rem;
  opacity: 0.95;
  margin: 0 0 32px;
  font-weight: 300;
  letter-spacing: 0.02em;
}

.hero .instructors {
  display: flex;
  justify-content: center;
  gap: 28px;
  flex-wrap: wrap;
  margin-bottom: 36px;
}

.hero .instructor {
  font-size: 0.95rem;
}

.hero .instructor strong {
  display: block;
  font-weight: 600;
  font-size: 1.05rem;
  margin-bottom: 2px;
}

.hero .instructor span {
  opacity: 0.85;
  font-size: 0.85rem;
  letter-spacing: 0.03em;
}

.hero .cta {
  display: inline-block;
  background: #fff;
  color: var(--primary);
  padding: 13px 28px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 1rem;
  box-shadow: var(--shadow-md);
  transition: transform 0.15s, box-shadow 0.15s;
}
.hero .cta:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: var(--primary-dark);
}

/* ============================================================
   Section blocks
   ============================================================ */

.section {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 56px 24px;
}

.section-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin: 0 0 8px;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 12px;
}

.section-title .icon {
  font-size: 1.5rem;
}

.section-subtitle {
  color: var(--color-muted);
  font-size: 0.95rem;
  margin: 0 0 28px;
}

/* ============================================================
   Quick Access cards
   ============================================================ */

.quick-access {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.qa-card {
  background: var(--box-bg);
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  padding: 22px 24px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s, box-shadow 0.15s, border-color 0.15s;
  display: flex;
  flex-direction: column;
  gap: 8px;
  text-decoration: none;
  color: inherit;
}

.qa-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
  color: inherit;
}

.qa-card .qa-label {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
}

.qa-card .qa-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-text);
}

.qa-card .qa-sub {
  color: var(--color-muted);
  font-size: 0.9rem;
}

/* ============================================================
   Course Sequences (chapter cards)
   ============================================================ */

.sequences {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 22px;
}

.seq-card {
  background: var(--box-bg);
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  padding: 24px 26px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s, box-shadow 0.15s;
  position: relative;
  overflow: hidden;
}

.seq-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.seq-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--primary);
}

.seq-card .seq-meta {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
  margin-bottom: 8px;
}

.seq-card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0 0 6px;
  color: var(--color-text);
}

.seq-card .seq-topics {
  color: var(--color-muted);
  font-size: 0.92rem;
  margin: 0 0 18px;
  min-height: 2.5em;
}

.seq-card .seq-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.seq-card .btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: 6px;
  font-size: 0.88rem;
  font-weight: 600;
  border: 1px solid var(--primary);
  color: var(--primary);
  background: #fff;
  transition: background 0.15s, color 0.15s;
}

.seq-card .btn:hover {
  background: var(--primary);
  color: #fff;
}

.seq-card .btn.primary {
  background: var(--primary);
  color: #fff;
}
.seq-card .btn.primary:hover {
  background: var(--primary-dark);
}

.seq-card .seq-soon {
  display: inline-block;
  padding: 8px 14px;
  border-radius: 6px;
  font-size: 0.88rem;
  background: var(--color-rule);
  color: var(--color-muted);
}

/* ============================================================
   Footer
   ============================================================ */

.site-footer {
  background: var(--primary-dark);
  color: rgba(255, 255, 255, 0.85);
  padding: 32px 24px;
  text-align: center;
  font-size: 0.9rem;
  margin-top: 60px;
}

.site-footer strong { color: #fff; }
.site-footer .footer-meta {
  display: block;
  margin-top: 6px;
  font-size: 0.82rem;
  opacity: 0.7;
  font-family: var(--font-mono);
}

/* ============================================================
   Lesson pages
   ============================================================ */

.lesson-hero {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #fff;
  padding: 50px 24px 40px;
}

.lesson-hero .container {
  max-width: 900px;
  margin: 0 auto;
}

.lesson-hero .lesson-label {
  font-size: 0.85rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  opacity: 0.85;
  margin-bottom: 8px;
}

.lesson-hero h1 {
  font-size: 2.4rem;
  font-weight: 700;
  margin: 0 0 8px;
  line-height: 1.2;
}

.lesson-hero .lesson-sub {
  font-size: 1rem;
  opacity: 0.9;
}

.lesson-content {
  max-width: 880px;
  margin: 0 auto;
  padding: 50px 24px 60px;
  background: var(--color-bg);
}

.lesson-content h1 { font-size: 2rem; color: var(--primary); margin-top: 1.5em; }
.lesson-content h2 {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--primary);
  margin: 2em 0 0.6em;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--primary-soft-2);
}
.lesson-content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--primary-dark);
  margin: 1.5em 0 0.5em;
}
.lesson-content h4 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--primary-dark);
  margin: 1.2em 0 0.4em;
}

.lesson-content p { margin: 0.8em 0; }
.lesson-content ul, .lesson-content ol { padding-left: 1.6em; margin: 0.8em 0; }
.lesson-content li { margin: 0.3em 0; }

.lesson-content pre {
  background: var(--code-block-bg);
  color: var(--code-block-fg);
  border-radius: var(--radius);
  padding: 16px 20px;
  overflow-x: auto;
  margin: 1.2em 0;
  font-family: var(--font-mono);
  font-size: 0.92em;
  line-height: 1.55;
  box-shadow: var(--shadow-sm);
}

.lesson-content pre code {
  background: none;
  color: inherit;
  font-size: inherit;
  padding: 0;
}

.lesson-content code {
  background: var(--color-code-bg);
  border: 1px solid var(--color-code-border);
  border-radius: 4px;
  padding: 1px 6px;
  font-family: var(--font-mono);
  font-size: 0.9em;
  color: var(--primary-dark);
}

.lesson-content blockquote {
  border-left: 4px solid var(--primary);
  background: var(--primary-soft);
  margin: 1.2em 0;
  padding: 12px 18px;
  border-radius: 0 6px 6px 0;
  color: var(--color-text);
}

.lesson-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.2em 0;
  font-size: 0.95em;
  box-shadow: var(--shadow-sm);
  border-radius: var(--radius);
  overflow: hidden;
}
.lesson-content th, .lesson-content td {
  border: 1px solid var(--color-rule);
  padding: 10px 14px;
  text-align: left;
}
.lesson-content th {
  background: var(--primary-soft);
  color: var(--primary-dark);
  font-weight: 600;
}

.lesson-content hr {
  border: none;
  border-top: 1px solid var(--color-rule);
  margin: 2em 0;
}

/* Strip inherited inline colors from imported Moodle HTML
   so they don't clash with the teal palette */
.lesson-content [style*="color: #2c3e50"],
.lesson-content [style*="color: #0d47a1"],
.lesson-content [style*="color: #1a237e"],
.lesson-content [style*="color: #0066cc"],
.lesson-content [style*="color:#0d47a1"] {
  color: inherit !important;
}

/* Wrapper boxes coming from the backup */
.lesson-content > div[style] {
  background: transparent !important;
  padding: 0 !important;
  border-radius: 0 !important;
}

/* Inline pages within a chapter — separator + sub-heading */
.lesson-page {
  margin-bottom: 48px;
  padding-bottom: 32px;
  border-bottom: 1px dashed var(--color-rule);
}
.lesson-page:last-of-type {
  border-bottom: none;
  margin-bottom: 0;
}

.lesson-page-title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  color: var(--primary);
}

.lesson-page-title .num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--primary);
  color: #fff;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  font-size: 0.9rem;
  font-weight: 700;
  font-family: var(--font-mono);
  flex-shrink: 0;
}

/* Lesson navigation (prev/next) */
.lesson-nav {
  max-width: 880px;
  margin: 0 auto;
  padding: 24px;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.lesson-nav a {
  flex: 1 1 200px;
  display: flex;
  flex-direction: column;
  padding: 14px 18px;
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  background: var(--box-bg);
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s, box-shadow 0.15s, border-color 0.15s;
}

.lesson-nav a:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
}

.lesson-nav a .dir {
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-bottom: 4px;
}

.lesson-nav a .ttl {
  color: var(--primary);
  font-weight: 600;
}

.lesson-nav a.next { text-align: right; }

/* Other activities list (quizzes, etc.) */
.other-activities {
  background: var(--primary-soft);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 30px 0;
}

.other-activities h3 {
  margin: 0 0 10px;
  font-size: 1rem;
  color: var(--primary-dark);
  font-weight: 600;
}

.other-activities ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 8px;
}

.other-activities li {
  font-size: 0.9rem;
  color: var(--color-muted);
}

.other-activities li::before {
  content: "•";
  color: var(--primary);
  margin-right: 8px;
  font-weight: bold;
}

/* ============================================================
   Callouts pédagogiques (définition, théorème, méthode, piège…)
   ============================================================ */

.box {
  border: 1px solid var(--color-rule);
  border-left: 5px solid var(--primary);
  background: var(--box-bg);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 14px 20px;
  margin: 1.4em 0;
  box-shadow: var(--shadow-sm);
}

.box > .box-title {
  display: block;
  font-weight: 700;
  font-size: 0.82rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--primary);
  margin-bottom: 6px;
}

.box > :last-child { margin-bottom: 0; }
.box > p:first-of-type { margin-top: 0; }

.box.def      { border-left-color: var(--def-br); background: var(--def-bg); }
.box.def > .box-title { color: var(--def-fg); }

.box.thm      { border-left-color: var(--thm-br); background: var(--thm-bg); }
.box.thm > .box-title { color: var(--thm-fg); }
.box.thm      { font-style: normal; }

.box.prop     { border-left-color: var(--prop-br); background: var(--prop-bg); }
.box.prop > .box-title { color: var(--prop-fg); }

.box.method   { border-left-color: var(--method-br); background: var(--method-bg); }
.box.method > .box-title { color: var(--method-fg); }

.box.warn     { border-left-color: var(--warn-br); background: var(--warn-bg); }
.box.warn > .box-title { color: var(--warn-fg); }

.box.tip      { border-left-color: var(--tip-br); background: var(--tip-bg); }
.box.tip > .box-title { color: var(--tip-fg); }

.box.example  { border-left-color: var(--example-br); background: var(--example-bg); }
.box.example > .box-title { color: var(--example-fg); }

.box.proof {
  border-left-color: var(--color-rule);
  background: var(--proof-bg);
  font-size: 0.97em;
}
.box.proof > .box-title { color: var(--color-muted); }
.box.proof::after {
  content: "\25A1";
  display: block;
  text-align: right;
  color: var(--color-muted);
  margin-top: 4px;
}

/* Grille "points clés" en fin de chapitre */
.keypoints {
  background: linear-gradient(135deg, var(--primary-soft) 0%, #fff 100%);
  border: 1px solid var(--primary-soft-2);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 2em 0;
}
.keypoints h3 { margin-top: 0 !important; }
.keypoints ul { margin: 0; }

/* ============================================================
   Exercices : cartes, badges de difficulté, corrigés repliables
   ============================================================ */

.exo {
  background: var(--box-bg);
  border: 1px solid var(--color-rule);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 1.4em 0;
  box-shadow: var(--shadow-sm);
}

.exo > h3, .exo > h4 { margin-top: 0 !important; }

.exo .exo-head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 6px;
}

.exo .exo-num {
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--primary);
}

.diff {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 2px 9px;
  border-radius: 999px;
  vertical-align: middle;
}
.diff.d1 { background: var(--d1-bg); color: var(--d1-fg); }
.diff.d2 { background: var(--d2-bg); color: var(--d2-fg); }
.diff.d3 { background: var(--d3-bg); color: var(--d3-fg); }
.diff.d4 { background: var(--d4-bg); color: var(--d4-fg); }

details.sol {
  margin: 12px 0 0;
  border: 1px dashed var(--primary-light);
  border-radius: 8px;
  background: var(--color-callout-bg);
  padding: 0 16px;
}
details.sol > summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--primary);
  padding: 10px 0;
  list-style: none;
  user-select: none;
}
details.sol > summary::-webkit-details-marker { display: none; }
details.sol > summary::before {
  content: "\25B8";
  display: inline-block;
  margin-right: 8px;
  transition: transform 0.15s;
}
details.sol[open] > summary::before { transform: rotate(90deg); }
details.sol[open] { padding-bottom: 10px; }

/* Bandeau lien vers la fiche d'exercices */
.exo-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  background: var(--primary);
  color: #fff;
  border-radius: var(--radius);
  padding: 18px 24px;
  margin: 2.2em 0 0;
  box-shadow: var(--shadow-md);
}
.exo-banner strong { display: block; font-size: 1.1rem; }
.exo-banner span { opacity: 0.9; font-size: 0.92rem; }
.exo-banner a {
  background: #fff;
  color: var(--primary);
  font-weight: 600;
  padding: 10px 20px;
  border-radius: 6px;
  white-space: nowrap;
}
.exo-banner a:hover { background: var(--primary-soft); color: var(--primary-dark); }

/* ============================================================
   Visualisations interactives (animations pas-à-pas)
   ============================================================ */

.viz {
  border: 1px solid var(--primary-soft-2);
  border-radius: var(--radius);
  background: var(--viz-bg);
  padding: 18px 20px;
  margin: 1.6em 0;
  box-shadow: var(--shadow-sm);
}

.viz-title {
  font-weight: 700;
  color: var(--primary);
  font-size: 0.82rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.viz-stage {
  min-height: 90px;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  gap: 6px;
  flex-wrap: wrap;
  padding: 10px 0;
}

.viz-controls {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--color-rule);
}

.viz-controls button {
  font-family: inherit;
  font-size: 0.88rem;
  font-weight: 600;
  padding: 7px 16px;
  border-radius: 6px;
  border: 1px solid var(--primary);
  background: var(--box-bg);
  color: var(--primary);
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}
.viz-controls button:hover:not(:disabled) { background: var(--primary); color: #fff; }
.viz-controls button:disabled { opacity: 0.4; cursor: not-allowed; }
.viz-controls button.primary { background: var(--primary); color: #fff; }
.viz-controls button.primary:hover:not(:disabled) { background: var(--primary-dark); }

.viz-controls input[type="range"] { accent-color: var(--primary); }
.viz-controls input[type="text"], .viz-controls input[type="number"] {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  padding: 6px 10px;
  border: 1px solid var(--color-rule);
  border-radius: 6px;
  background: #fff;
}

.viz-status {
  font-family: var(--font-mono);
  font-size: 0.86rem;
  background: var(--color-code-bg);
  border: 1px solid var(--color-code-border);
  border-radius: 6px;
  padding: 10px 14px;
  margin-top: 12px;
  min-height: 2.6em;
  color: var(--primary-dark);
  white-space: pre-wrap;
}

.viz-step-counter {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--color-muted);
  margin-left: auto;
}

/* Barres (tris, tableaux de nombres) */
.bar {
  width: 34px;
  background: var(--primary-light);
  color: #fff;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-align: center;
  border-radius: 4px 4px 0 0;
  transition: height 0.25s, background 0.25s;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  padding-bottom: 3px;
}
.bar.cmp    { background: var(--viz-cmp); }
.bar.swap   { background: var(--viz-bad); }
.bar.sorted { background: var(--viz-ok); }
.bar.pivot  { background: var(--viz-alt); }
.bar.dim    { background: var(--color-rule); color: var(--color-muted); }

/* Cellules (listes, piles, files, dichotomie) */
.cell {
  min-width: 42px;
  height: 42px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  border: 2px solid var(--color-rule);
  border-radius: 6px;
  background: var(--box-bg);
  transition: background 0.2s, border-color 0.2s, transform 0.2s;
}
.cell.active   { border-color: var(--viz-cmp); background: var(--tip-bg); }
.cell.found    { border-color: var(--viz-ok); background: var(--method-bg); }
.cell.excluded { opacity: 0.32; }
.cell.bound    { border-color: var(--primary); background: var(--primary-soft); }

.cell-idx {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--color-muted);
  text-align: center;
}

/* Pile d'appels récursifs */
.frame {
  border: 1px solid var(--primary-soft-2);
  border-left: 4px solid var(--primary);
  background: var(--box-bg);
  border-radius: 0 6px 6px 0;
  padding: 6px 12px;
  font-family: var(--font-mono);
  font-size: 0.84rem;
  margin: 3px 0;
}
.frame.returning { border-left-color: var(--viz-ok); background: var(--method-bg); }

@media (max-width: 720px) {
  .exo-banner { flex-direction: column; align-items: flex-start; }
  .bar { width: 24px; font-size: 0.62rem; }
  .cell { min-width: 34px; height: 34px; font-size: 0.8rem; }
}

/* ============================================================
   Mobile
   ============================================================ */

@media (max-width: 720px) {
  .hero { padding: 50px 18px 60px; }
  .hero h1 { font-size: 2.2rem; }
  .hero .subtitle { font-size: 1.05rem; }
  .section { padding: 40px 18px; }
  .lesson-hero { padding: 40px 18px 32px; }
  .lesson-hero h1 { font-size: 1.7rem; }
  .lesson-content { padding: 36px 18px 50px; }
  body { font-size: 16px; }
}

/* ============================================================
   Print
   ============================================================ */

@media print {
  .site-header, .lesson-nav, .lesson-hero, .hero, .site-footer { display: none; }
  .lesson-content { padding: 0; max-width: 100%; }
  body { background: #fff; }
}