/* ==========================================================================
   Nabla — base.css
   Reset, typographie, en-tête/pied de page, composants partagés, accueil.
   Toutes les couleurs viennent de tokens.css.
   ========================================================================== */

/* --- Reset & fondations --------------------------------------------------- */

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

html {
  margin: 0;
  padding: 0;
  background: var(--bg);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-serif);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}
a:hover { color: var(--text); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

button { font: inherit; }

@keyframes nablaDraw { to { stroke-dashoffset: 0; } }
@keyframes nablaFade { to { opacity: 1; } }

/* Logo ∇ monotrait — un seul trait, même main que les courbes.
   Dans l'en-tête il se trace au chargement (comme la courbe du héro). */
.logo-nabla {
  display: block;
  flex-shrink: 0;
  color: var(--accent);
}
.marque .logo-nabla path {
  stroke-dasharray: 1;
  stroke-dashoffset: 1;
  animation: nablaDraw 0.9s cubic-bezier(0.55, 0.06, 0.28, 0.99) 0.15s forwards;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-delay: 0ms !important;
    transition: none !important;
  }
  html { scroll-behavior: auto; }
}

/* --- Composants partagés --------------------------------------------------- */

/* Bouton pilule (toggle de thème, réinitialiser) */
.btn-pill {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--muted);
  background: none;
  border: 1px solid var(--hair);
  border-radius: 999px;
  padding: 5px 12px;
  cursor: pointer;
  white-space: nowrap;
}
.btn-pill:hover { border-color: var(--text); color: var(--text); }

/* Étiquette mono (kickers, labels de section) */
.kicker {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--faint);
}

/* --- En-tête de site -------------------------------------------------------- */

.site-header {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: 22px var(--pad-x);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.marque {
  text-decoration: none;
  color: var(--text);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.marque:hover { color: var(--text); }
.marque .marque-nom {
  font-weight: 600;
  font-size: 19px;
  letter-spacing: 0.01em;
}

.nav-site {
  display: flex;
  align-items: center;
  gap: clamp(16px, 3vw, 28px);
  font-family: var(--font-mono);
  font-size: 13px;
}
.nav-site a {
  text-decoration: none;
  color: var(--text);
}
.nav-site a:hover { color: var(--accent); }

/* --- Pied de page ------------------------------------------------------------ */

.site-footer { border-top: 1px solid var(--hair); }
.site-footer .footer-inner {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: 24px var(--pad-x);
  display: flex;
  flex-wrap: wrap;
  gap: 12px 28px;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--faint);
}
.site-footer .footer-marque { display: inline-flex; align-items: center; gap: 7px; }
.site-footer .footer-liens { display: flex; gap: 20px; flex-wrap: wrap; }
.site-footer a { color: var(--faint); }
.site-footer a:hover { color: var(--text); }

/* --- Accueil : héro ------------------------------------------------------------ */

.hero {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: clamp(36px, 6vw, 76px) var(--pad-x) clamp(44px, 6vw, 72px);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: clamp(32px, 5vw, 64px);
}
.hero-texte { flex: 1.15; min-width: 300px; }
.hero-texte h1 {
  margin: 16px 0 0;
  font-size: clamp(34px, 5.5vw, 54px);
  line-height: 1.07;
  font-weight: 600;
  letter-spacing: -0.015em;
  text-wrap: balance;
}
.hero-texte .hero-accroche {
  margin: 20px 0 0;
  font-size: clamp(16px, 2vw, 18.5px);
  line-height: 1.6;
  color: var(--muted);
  max-width: 46ch;
}
.hero-cta { margin-top: 28px; }
.hero-cta a { font-size: 17px; font-weight: 500; }
.hero-figure { flex: 1; min-width: 280px; }
.hero-figure svg { width: 100%; height: auto; display: block; }

/* Héro : SVG animé */
.hero-svg .g-grid { stroke: var(--grid); stroke-width: var(--sw-grid); fill: none; }
.hero-svg .g-axis { stroke: var(--axis); stroke-width: var(--sw-grid); fill: none; }
.hero-svg .g-courbe {
  stroke: var(--chalk);
  stroke-width: var(--sw-curve-hero);
  fill: none;
  stroke-linecap: round;
  stroke-dasharray: 1;
  stroke-dashoffset: 1;
  animation: nablaDraw 1.9s cubic-bezier(0.55, 0.06, 0.28, 0.99) 0.3s forwards;
}
.hero-svg .g-onde {
  stroke: var(--accent);
  stroke-width: var(--sw-tan);
  fill: none;
  stroke-linecap: round;
  stroke-dasharray: 1;
  stroke-dashoffset: 1;
  animation: nablaDraw 1.3s cubic-bezier(0.55, 0.06, 0.28, 0.99) 1.4s forwards;
}
.hero-svg .g-apparition { opacity: 0; animation: nablaFade 0.6s ease 2.8s forwards; }
.hero-svg .pt-halo { fill: none; stroke: var(--accent); stroke-opacity: 0.4; stroke-width: 1.5; }
.hero-svg .pt-point { fill: var(--accent); stroke: var(--bg); stroke-width: 2; }

/* --- Accueil : recherche + filtres --------------------------------------------- */

.outils-chapitres {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: 0 var(--pad-x) clamp(26px, 4vw, 40px);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 22px;
}

.recherche { position: relative; flex: 1 1 300px; max-width: 560px; }
.recherche-input {
  width: 100%;
  font: inherit;
  font-size: 15.5px;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--hair);
  border-radius: 999px;
  padding: 10px 18px 10px 42px;
  appearance: none;
  -webkit-appearance: none;
}
.recherche-input::placeholder { color: var(--faint); opacity: 1; }
.recherche-input:hover { border-color: var(--dash); }
.recherche-loupe {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  width: 15px;
  height: 15px;
  color: var(--faint);
  pointer-events: none;
}

.recherche-resultats {
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  right: 0;
  z-index: 20;
  background: var(--surface);
  border: 1px solid var(--edge);
  border-radius: var(--radius-block);
  max-height: min(60vh, 420px);
  overflow-y: auto;
  padding: 6px;
}
.resultat-groupe {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--faint);
  padding: 8px 10px 4px;
}
.resultat {
  display: block;
  padding: 8px 10px;
  border-radius: var(--radius-chip);
  text-decoration: none;
  color: var(--text);
}
.resultat:hover, .resultat.actif { background: var(--accTint); color: var(--text); }
.resultat-titre { font-size: 15.5px; font-weight: 500; }
.resultat-sous {
  margin-top: 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--faint);
}
.recherche-vide { padding: 10px 12px; font-size: 14.5px; color: var(--muted); }

.filtres { display: flex; flex-wrap: wrap; gap: 8px 20px; }
.filtre-groupe { display: flex; flex-wrap: wrap; gap: 8px; }
.filtres .btn-pill[aria-pressed="true"] {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accTint);
}

/* --- Accueil : rangées de chapitres ------------------------------------------- */

.catalogue { padding-bottom: clamp(48px, 7vw, 80px); }

.rangee-chapitres {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: 0 var(--pad-x) clamp(24px, 4vw, 40px);
}

/* Groupes par thème du programme officiel, dans chaque matière */
.groupe-theme { display: grid; gap: 14px; }
.groupe-theme + .groupe-theme { margin-top: 30px; }
.theme-tete {
  display: flex;
  align-items: center;
  gap: 14px;
  margin: 0 0 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--faint);
}
.theme-tete::after { content: ''; flex: 1; border-top: 1px solid var(--hairIn); }

.rangee-tete {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  border-top: 1px solid var(--edge);
  padding-top: 18px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}
.rangee-tete h2 {
  margin: 0;
  font-size: clamp(20px, 3vw, 24px);
  font-weight: 600;
}
/* Carte de chapitre en ligne */
.carte-chapitre {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: clamp(20px, 4vw, 56px);
  text-decoration: none;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--edge);
  border-radius: var(--radius-card);
  padding: clamp(22px, 4vw, 34px);
}
.carte-chapitre:hover { border-color: var(--accent); color: var(--text); }
.carte-info { flex: 1.4; min-width: 260px; }
.carte-statut {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--accent);
}
.carte-titre {
  font-size: clamp(24px, 4vw, 30px);
  font-weight: 600;
  margin-top: 8px;
}
.carte-desc {
  margin-top: 10px;
  color: var(--muted);
  font-size: 15.5px;
  line-height: 1.55;
}
.carte-ouvrir {
  margin-top: 16px;
  color: var(--accent);
  font-weight: 500;
  font-size: 16px;
}
.carte-motif { flex: 1; min-width: 190px; max-width: 270px; }
.carte-motif svg { width: 100%; height: auto; display: block; overflow: visible; }
.carte-motif .g-courbe { stroke: var(--chalk); stroke-width: var(--sw-motif); fill: none; stroke-linecap: round; }
.carte-motif .g-tangente { stroke: var(--accent); stroke-width: 1.4; fill: none; stroke-linecap: round; }
/* Seconde courbe d'un motif (le logarithme face à l'exponentielle) : même
   graisse que la craie, couleur d'accent — le rôle « courbe qui répond ». */
.carte-motif .g-courbe-derivee { stroke: var(--accent); stroke-width: var(--sw-motif); fill: none; stroke-linecap: round; }
.carte-motif .pt-point { fill: var(--accent); stroke: var(--surface); stroke-width: 1; }
.carte-motif .pt-craie { fill: var(--chalk); }

/* Cartes « bientôt » */
.grille-bientot {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(215px, 1fr));
  gap: 14px;
}
.carte-bientot {
  border: 1px dashed var(--dash2);
  border-radius: var(--radius-card);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.carte-bientot .bientot-tag {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--faint);
}
.carte-bientot .bientot-titre {
  font-size: 17.5px;
  font-weight: 500;
  color: var(--faint);
  flex: 1;
}
.carte-bientot svg { width: 68px; height: auto; display: block; }
.carte-bientot .g-motif { stroke: var(--ghost); stroke-width: var(--sw-motif); fill: none; stroke-linecap: round; }
.carte-bientot .pt-motif { fill: var(--ghost); }

/* --- Accueil : « comment ça marche » ------------------------------------------- */

.bande-comment {
  border-top: 1px solid var(--hair);
  border-bottom: 1px solid var(--hair);
}
.bande-comment .bande-inner {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: clamp(28px, 4vw, 40px) var(--pad-x);
  display: flex;
  flex-wrap: wrap;
  gap: 18px clamp(28px, 4vw, 56px);
}
.etape-comment {
  display: flex;
  align-items: baseline;
  gap: 12px;
  flex: 1;
  min-width: 230px;
}
.etape-comment .etape-num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--accent);
}
.etape-comment .etape-texte { font-size: 16px; line-height: 1.5; }
.etape-comment strong { font-weight: 600; }
.etape-comment .etape-detail { color: var(--muted); }

/* --- Accueil : à propos ----------------------------------------------------------- */

.apropos {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: clamp(48px, 7vw, 76px) var(--pad-x);
}
.apropos-inner { max-width: 680px; }
.apropos-inner .kicker { letter-spacing: 0.14em; font-size: 11px; }
.apropos-inner p {
  margin: 12px 0 0;
  font-size: 17px;
  line-height: 1.65;
}