/* ============================================================
   RÉVISE MATHS LYCÉE — Feuille de style principale
   Mobile-first, KaTeX compatible, thème clair sérieux
   ============================================================ */

:root {
  --color-primary: #1a56a0;
  --color-primary-dark: #133e7c;
  --color-accent: #e63946;
  --color-success: #2a9d4e;
  --color-error: #e63946;
  --color-bg: #f8f9fa;
  --color-surface: #ffffff;
  --color-border: #dee2e6;
  --color-text: #212529;
  --color-text-muted: #6c757d;
  --color-youtube: #ff0000;
  --radius: 10px;
  --shadow: 0 2px 8px rgba(0,0,0,.10);
  --shadow-lg: 0 4px 20px rgba(0,0,0,.13);
  --font: 'Segoe UI', Arial, sans-serif;
  --max-width: 900px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

/* ---- HEADER ---- */
header {
  background: var(--color-primary);
  color: #fff;
  padding: 16px 20px;
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.logo { font-size: 1.2rem; font-weight: 700; text-decoration: none; color: #fff; }
.logo span { color: #ffd166; }
.nav-yt a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--color-youtube);
  color: #fff;
  text-decoration: none;
  padding: 7px 14px;
  border-radius: 6px;
  font-size: .88rem;
  font-weight: 600;
  transition: background .2s;
}
.nav-yt a:hover { background: #cc0000; }

/* ---- MAIN CONTAINER ---- */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 24px 16px 48px;
}

/* ---- HERO ---- */
.hero {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 36px 28px;
  margin-bottom: 32px;
  box-shadow: var(--shadow);
  text-align: center;
}
.hero h1 {
  font-size: clamp(1.5rem, 4vw, 2.2rem);
  color: var(--color-primary);
  margin-bottom: 12px;
  line-height: 1.25;
}
.hero p {
  color: var(--color-text-muted);
  font-size: 1.05rem;
  max-width: 620px;
  margin: 0 auto 20px;
}
.badge-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-bottom: 22px;
}
.badge {
  background: #e9f0fb;
  color: var(--color-primary);
  border-radius: 20px;
  padding: 4px 14px;
  font-size: .85rem;
  font-weight: 600;
}
.cta-yt {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--color-youtube);
  color: #fff;
  text-decoration: none;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 700;
  transition: background .2s, transform .15s;
}
.cta-yt:hover { background: #cc0000; transform: translateY(-1px); }

/* ---- MODULE GRID (homepage) ---- */
.modules-section h2 {
  font-size: 1.35rem;
  color: var(--color-primary);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-border);
}
.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
}
.module-card {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 22px 20px;
  box-shadow: var(--shadow);
  text-decoration: none;
  color: var(--color-text);
  display: flex;
  flex-direction: column;
  gap: 10px;
  border: 2px solid transparent;
  transition: border-color .2s, transform .2s, box-shadow .2s;
}
.module-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}
.module-card .card-icon { font-size: 2rem; }
.module-card h3 { font-size: 1.1rem; color: var(--color-primary); }
.module-card p { font-size: .9rem; color: var(--color-text-muted); }
.card-level {
  display: inline-block;
  background: #e9f0fb;
  color: var(--color-primary);
  border-radius: 12px;
  padding: 2px 10px;
  font-size: .78rem;
  font-weight: 700;
  align-self: flex-start;
  margin-top: auto;
}

/* ---- PAGE EXERCICE ---- */
.exercise-page header + main { padding-top: 24px; }

.ex-header {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 24px 24px 20px;
  margin-bottom: 24px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.ex-header .back-link {
  font-size: .88rem;
  color: var(--color-primary);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}
.ex-header .back-link:hover { text-decoration: underline; }
.ex-header h1 { font-size: 1.5rem; color: var(--color-primary); }
.ex-header .subtitle { color: var(--color-text-muted); font-size: .95rem; }

/* ---- EXERCISE CARD ---- */
.ex-card {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 28px 24px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.enonce-label {
  font-size: .8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .05em;
  color: var(--color-text-muted);
  margin-bottom: 6px;
}
#enonce {
  font-size: 1.05rem;
  line-height: 1.7;
  min-height: 48px;
}

/* ---- CHAMPS DE RÉPONSE ---- */
.answer-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.answer-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}
.answer-row label { font-size: .95rem; white-space: nowrap; }
.answer-input {
  border: 2px solid var(--color-border);
  border-radius: 6px;
  padding: 8px 12px;
  font-size: 1rem;
  width: 140px;
  transition: border-color .2s;
  font-family: var(--font);
}
.answer-input:focus { outline: none; border-color: var(--color-primary); }
.answer-input.correct { border-color: var(--color-success); background: #f0faf4; }
.answer-input.incorrect { border-color: var(--color-error); background: #fff5f5; }

/* ---- BOUTONS ---- */
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 20px;
  border-radius: 7px;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: background .2s, transform .15s;
  font-family: var(--font);
}
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: var(--color-primary); color: #fff; }
.btn-primary:hover { background: var(--color-primary-dark); }
.btn-success { background: var(--color-success); color: #fff; }
.btn-success:hover { background: #22813f; }
.btn-outline {
  background: transparent;
  border: 2px solid var(--color-border);
  color: var(--color-text);
}
.btn-outline:hover { border-color: var(--color-primary); color: var(--color-primary); }
.btn-new { background: #fff3cd; color: #856404; border: 2px solid #ffc107; }
.btn-new:hover { background: #ffe69c; }

/* ---- FEEDBACK ---- */
.feedback-box {
  border-radius: 8px;
  padding: 14px 16px;
  font-size: .95rem;
  display: none;
  gap: 8px;
  align-items: flex-start;
}
.feedback-box.show { display: flex; }
.feedback-box.ok { background: #f0faf4; border: 1.5px solid #6fcf97; color: #1a5c34; }
.feedback-box.ko { background: #fff5f5; border: 1.5px solid #f08080; color: #8b0000; }
.feedback-icon { font-size: 1.3rem; flex-shrink: 0; }

/* ---- SOLUTION ---- */
.solution-box {
  background: #f0f4ff;
  border: 1.5px solid #b3c6f7;
  border-radius: 8px;
  padding: 18px 16px;
  display: none;
  /* Empêche le débordement horizontal (formules KaTeX larges) */
  width: 100%;
  max-width: 100%;
  overflow-x: auto;
  box-sizing: border-box;
  overflow-wrap: break-word;
  word-break: break-word;
}
.solution-box.show { display: block; }
.solution-box h4 {
  color: var(--color-primary);
  font-size: 1rem;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 6px;
}
.solution-content {
  display: flex;
  flex-direction: column;
  gap: 10px;
  font-size: .95rem;
  line-height: 1.7;
  /* min-width:0 évite le bug flex où les enfants ne se contractent pas */
  min-width: 0;
}
.solution-step {
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 8px;
  align-items: baseline;
  /* min-width:0 critique en grid : force la colonne 1fr à respecter sa limite */
  min-width: 0;
}
/* La cellule de texte dans le grid doit aussi pouvoir se contracter */
.solution-step > div:last-child {
  min-width: 0;
  overflow-wrap: break-word;
  word-break: break-word;
}
.step-num {
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .78rem;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 2px;
}

/* ---- CTA CHAÎNE ---- */
.cta-channel {
  background: linear-gradient(135deg, #fff5f5, #fff0f0);
  border: 1.5px solid #ffc0c0;
  border-radius: var(--radius);
  padding: 24px 20px;
  text-align: center;
  margin-top: 28px;
  box-shadow: var(--shadow);
}
.cta-channel p { color: var(--color-text-muted); margin-bottom: 14px; font-size: .95rem; }
.cta-channel strong { color: var(--color-text); }

/* ---- FOOTER ---- */
footer {
  background: var(--color-primary-dark);
  color: rgba(255,255,255,.8);
  text-align: center;
  padding: 20px 16px;
  font-size: .88rem;
  margin-top: 40px;
}
footer a { color: #ffd166; text-decoration: none; }
footer a:hover { text-decoration: underline; }

/* ---- KATEX OVERRIDES ---- */
/* overflow-x:auto permet de scroller les formules très larges DANS la boîte */
.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  max-width: 100%;
  /* évite que la formule pousse la boîte parente vers l'extérieur */
  padding-bottom: 4px;   /* laisse un peu d'espace pour la barre de scroll */
}
/* Permet aux formules inline de passer à la ligne si nécessaire */
.katex { font-size: 1.05em; white-space: normal; }

/* ---- RESPONSIVE ---- */
@media (max-width: 600px) {
  .header-inner { justify-content: center; }
  .hero { padding: 24px 16px; }
  .ex-card { padding: 20px 16px; }
  .solution-step { grid-template-columns: 24px 1fr; }
  .answer-input { width: 120px; }
}