/* ============================================================================
   LABORATOIRE ATOMIQUE, QUANTIQUE & RELATIVISTE — FEUILLE DE STYLE (Phases 2-5)
   Grille CSS dynamique 18 / 32 colonnes, Heatmap log/linéaire, Bohr SVG, Hund
   ============================================================================ */

:root {
  --primary: #1a1d2e;
  --primary-light: #252a3f;
  --accent: #6366f1;
  --accent-light: #818cf8;
  --accent-glow: #4f46e5;
  --secondary: #ec4899;
  --tertiary: #14b8a6;
  --gold: #f59e0b;
  --bg-start: #0f172a;
  --bg-end: #1e293b;
  --card-bg: rgba(255, 255, 255, 0.97);
  --text-dark: #0f172a;
  --text-muted: #475569;
  --border: rgba(100, 116, 139, 0.15);
  --shadow: 0 20px 40px rgba(0, 0, 0, 0.15), 0 8px 16px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 30px 60px rgba(0, 0, 0, 0.28), 0 12px 24px rgba(0, 0, 0, 0.18);
  --radius: 20px;
  --glow: 0 0 20px rgba(99, 102, 241, 0.35);

  /* Couleurs par familles chimiques */
  --fam-alkali: #3b82f6;
  --fam-alkaline: #10b981;
  --fam-transition: #eab308;
  --fam-post-transition: #06b6d4;
  --fam-metalloid: #f97316;
  --fam-nonmetal: #a855f7;
  --fam-halogen: #ef4444;
  --fam-noble: #64748b;
  --fam-lanthanide: #ec4899;
  --fam-actinide: #db2777;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  color: var(--text-dark);
  background: linear-gradient(135deg, var(--bg-start) 0%, var(--bg-end) 100%);
  min-height: 100vh;
  line-height: 1.6;
}

/* Header Sticky */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  backdrop-filter: blur(20px) saturate(180%);
  background: linear-gradient(135deg, rgba(26, 29, 46, 0.96), rgba(37, 42, 63, 0.93));
  border-bottom: 1px solid rgba(99, 102, 241, 0.25);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.site-header.scrolled {
  box-shadow: var(--shadow);
  border-bottom-color: rgba(99, 102, 241, 0.5);
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 24px;
}

.mast {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 0;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
}

.logo {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-glow));
  color: white;
  font-weight: 800;
  box-shadow: 0 0 20px rgba(99, 102, 241, 0.5), inset 0 0 0 2px rgba(255, 255, 255, 0.2);
  font-size: 1.45rem;
  transition: transform 0.4s ease, box-shadow 0.3s ease;
}

.logo:hover {
  transform: rotate(360deg) scale(1.1);
  box-shadow: 0 0 30px rgba(99, 102, 241, 0.85);
}

.title {
  font-weight: 800;
  letter-spacing: -0.02em;
  color: white;
  font-size: 1.12rem;
}

.subtitle-brand {
  font-size: 0.76rem;
  color: #a5b4fc;
  display: block;
  font-weight: 500;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 7px;
  flex-wrap: wrap;
}

nav a {
  display: inline-block;
  text-decoration: none;
  color: rgba(255, 255, 255, 0.92);
  font-weight: 600;
  font-size: 0.8rem;
  padding: 7px 11px;
  border-radius: 10px;
  background: rgba(99, 102, 241, 0.12);
  border: 1px solid rgba(99, 102, 241, 0.22);
  transition: all 0.25s ease;
  position: relative;
  overflow: hidden;
}

nav a:hover {
  background: rgba(99, 102, 241, 0.3);
  border-color: rgba(99, 102, 241, 0.55);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.35);
}

/* Hero */
.hero {
  background: linear-gradient(135deg, #1a1d2e 0%, #2d3250 50%, #1a1d2e 100%);
  color: white;
  padding: 56px 0 42px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background:
    radial-gradient(circle at 20% 50%, rgba(99, 102, 241, 0.18) 0%, transparent 50%),
    radial-gradient(circle at 80% 50%, rgba(236, 72, 153, 0.18) 0%, transparent 50%);
  animation: pulse 8s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.6; }
}

.hero .container {
  position: relative;
  z-index: 1;
}

.hero h1 {
  margin: 0 0 14px;
  font-size: clamp(1.9rem, 3.6vw, 2.85rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, #fff 0%, #c7d2fe 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  margin: 0;
  opacity: 0.92;
  max-width: 960px;
  font-size: 1.02rem;
  line-height: 1.7;
}

/* Chipbar interactive */
.chipbar {
  display: flex;
  gap: 9px;
  flex-wrap: wrap;
  margin-top: 22px;
  align-items: center;
}

.chip {
  font-size: 0.82rem;
  font-weight: 600;
  padding: 8px 14px;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.18);
  color: white;
  backdrop-filter: blur(10px);
  transition: all 0.25s ease;
  cursor: pointer;
  user-select: none;
}

.chip:hover, .chip.active {
  background: rgba(99, 102, 241, 0.48);
  border-color: #a5b4fc;
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(99, 102, 241, 0.35);
}

/* Barre d'outils scientifique (Grille 18/32, Heatmap Log/Linéaire, Thermomètre, Recherche) */
.lab-toolbar {
  background: rgba(15, 23, 42, 0.88);
  border: 1px solid rgba(99, 102, 241, 0.32);
  border-radius: 16px;
  padding: 18px 22px;
  margin-bottom: 20px;
  color: #f8fafc;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(235px, 1fr));
  gap: 18px;
  align-items: start;
  box-shadow: var(--shadow);
}

.tool-box label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #a5b4fc;
  margin-bottom: 7px;
}

.tool-box select, .tool-box input[type="text"] {
  width: 100%;
  padding: 9px 12px;
  border-radius: 10px;
  border: 1px solid rgba(148, 163, 184, 0.32);
  background: rgba(30, 41, 59, 0.92);
  color: white;
  font-size: 0.88rem;
  font-weight: 500;
}

.tool-box input[type="range"] {
  width: 100%;
  accent-color: var(--accent-light);
  cursor: pointer;
}

.toggle-group {
  display: flex;
  gap: 6px;
  background: rgba(30, 41, 59, 0.9);
  padding: 4px;
  border-radius: 10px;
  border: 1px solid rgba(148, 163, 184, 0.28);
}

.toggle-btn {
  flex: 1;
  border: none;
  background: transparent;
  color: #cbd5e1;
  font-size: 0.8rem;
  font-weight: 700;
  padding: 7px 10px;
  border-radius: 7px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.toggle-btn.active {
  background: linear-gradient(135deg, var(--accent), var(--accent-glow));
  color: white;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.4);
}

.scale-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 7px;
  font-size: 0.76rem;
  color: #cbd5e1;
}

.heatmap-gradient-bar {
  height: 7px;
  border-radius: 999px;
  width: 100%;
  margin-top: 6px;
  background: linear-gradient(90deg, hsl(230, 82%, 44%), hsl(160, 80%, 42%), hsl(60, 88%, 48%), hsl(10, 88%, 48%));
  display: none;
}

.phase-legend {
  display: flex;
  gap: 11px;
  flex-wrap: wrap;
  font-size: 0.75rem;
  margin-top: 6px;
  color: #cbd5e1;
}

.phase-dot {
  display: inline-block;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  margin-right: 4px;
}

/* ============================================================================
   PHASE 2 : GRILLE CSS PÉRIODIQUE DYNAMIQUE (18 COLONNES / 32 COLONNES)
   ============================================================================ */
.ptable-scroll-wrapper {
  overflow-x: auto;
  padding: 6px 0 18px;
}

.ptable-css-grid {
  display: grid;
  gap: 5px;
  background: rgba(15, 23, 42, 0.76);
  padding: 14px;
  border-radius: 18px;
  border: 1px solid rgba(99, 102, 241, 0.28);
  box-shadow: var(--shadow-lg);
  transition: grid-template-columns 0.35s ease;
  min-width: 980px;
}

.ptable-css-grid.mode-18 {
  /* Colonne 1 = étiquette de période, Colonnes 2..19 = Groupes 1 à 18 */
  grid-template-columns: 38px repeat(18, minmax(48px, 1fr));
}

.ptable-css-grid.mode-32 {
  /* Colonne 1 = étiquette de période, Colonnes 2..33 = 32 colonnes UICPA (s + f + d + p) */
  grid-template-columns: 36px repeat(32, minmax(38px, 1fr));
  min-width: 1360px;
}

.grid-col-header,
.grid-row-header {
  background: linear-gradient(135deg, var(--primary-light), var(--primary));
  color: #a5b4fc;
  font-weight: 800;
  font-size: 0.74rem;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(99, 102, 241, 0.22);
  min-height: 32px;
  user-select: none;
}

.grid-row-header {
  color: #f8fafc;
  font-size: 0.78rem;
}

.f-block-divider {
  grid-column: 1 / -1;
  height: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  color: #94a3b8;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.el-cell {
  background: rgba(255, 255, 255, 0.96);
  color: var(--text-dark);
  border-radius: 8px;
  padding: 5px 4px;
  min-height: 60px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  position: relative;
  border: 2px solid transparent;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.12);
  transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.2s ease, opacity 0.25s ease, background-color 0.25s ease;
  user-select: none;
}

.ptable-css-grid.mode-32 .el-cell {
  min-height: 54px;
  padding: 4px 2px;
}

/* Bordure supérieure colorée par famille chimique */
.el-cell[data-family="alkali"]          { border-top: 4px solid var(--fam-alkali); }
.el-cell[data-family="alkaline"]        { border-top: 4px solid var(--fam-alkaline); }
.el-cell[data-family="transition"]      { border-top: 4px solid var(--fam-transition); }
.el-cell[data-family="post-transition"] { border-top: 4px solid var(--fam-post-transition); }
.el-cell[data-family="metalloid"]       { border-top: 4px solid var(--fam-metalloid); }
.el-cell[data-family="nonmetal"]        { border-top: 4px solid var(--fam-nonmetal); }
.el-cell[data-family="halogen"]         { border-top: 4px solid var(--fam-halogen); }
.el-cell[data-family="noble"]           { border-top: 4px solid var(--fam-noble); }
.el-cell[data-family="lanthanide"]      { border-top: 4px solid var(--fam-lanthanide); }
.el-cell[data-family="actinide"]        { border-top: 4px solid var(--fam-actinide); }

.el-cell.f-block-ref {
  background: rgba(255, 255, 255, 0.93);
  border: 1px dashed rgba(100, 116, 139, 0.45);
}

.el-cell.dimmed {
  opacity: 0.15;
  filter: grayscale(85%);
  transform: scale(0.94);
}

.el-cell.selected-el {
  outline: 3px solid #f59e0b;
  transform: scale(1.1);
  z-index: 20;
  box-shadow: 0 0 18px rgba(245, 158, 11, 0.65);
}

.el-cell:hover {
  background: linear-gradient(135deg, var(--accent-light), var(--accent)) !important;
  color: white !important;
  transform: scale(1.16);
  box-shadow: 0 8px 20px rgba(99, 102, 241, 0.55);
  z-index: 30;
}

.el-cell:hover .el-metric,
.el-cell:hover .atomic-number {
  color: #e0e7ff !important;
}

.el-cell .atomic-number {
  font-size: 0.66rem;
  font-weight: 700;
  opacity: 0.78;
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  padding: 0 2px;
}

.el-cell .symbol {
  font-size: 1.12rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.ptable-css-grid.mode-32 .el-cell .symbol {
  font-size: 0.96rem;
}

.el-cell .el-metric {
  font-size: 0.6rem;
  font-weight: 600;
  color: #475569;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 100%;
}

/* Indicateur d'état physique (Solide, Liquide, Gaz) */
.state-badge {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  display: inline-block;
  flex-shrink: 0;
}
.state-solid   { background: #0f172a; }
.state-liquid  { background: #2563eb; box-shadow: 0 0 4px #3b82f6; }
.state-gas     { background: #ef4444; box-shadow: 0 0 4px #ef4444; }
.state-unknown { background: #94a3b8; }

/* Tooltip au survol */
.el-cell[data-name]::after {
  content: attr(data-name);
  position: absolute;
  bottom: 106%;
  left: 50%;
  transform: translateX(-50%) translateY(-6px);
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: white;
  padding: 5px 11px;
  border-radius: 8px;
  font-size: 0.76rem;
  font-weight: 600;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.22s ease, transform 0.22s ease;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.38);
  z-index: 100;
}

.el-cell[data-name]:hover::after {
  opacity: 1;
  transform: translateX(-50%) translateY(-2px);
}

/* ============================================================================
   PHASE 3 & 4 : INSPECTEUR QUANTIQUE, BOHR SVG & MONOGRAPHIE WIKIPÉDIA
   ============================================================================ */
.quantum-inspector {
  margin-top: 22px;
  background: linear-gradient(135deg, rgba(26, 29, 46, 0.96), rgba(15, 23, 42, 0.98));
  border: 1px solid rgba(99, 102, 241, 0.35);
  border-radius: var(--radius);
  padding: 26px;
  color: #f8fafc;
  box-shadow: var(--shadow-lg);
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 28px;
  align-items: start;
}

@media (max-width: 980px) {
  .quantum-inspector { grid-template-columns: 1fr; }
}

.bohr-box {
  background: rgba(9, 13, 22, 0.78);
  border: 1px solid rgba(99, 102, 241, 0.28);
  border-radius: 16px;
  padding: 16px;
  text-align: center;
}

#bohrSvgContainer {
  width: 268px;
  height: 268px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
}

#bohrSvgContainer svg {
  width: 100%;
  height: 100%;
  overflow: visible;
}

.bohr-orbit-anim {
  transform-origin: 134px 134px;
  animation: spinOrbit 28s linear infinite;
}

.bohr-orbit-anim.paused {
  animation-play-state: paused;
}

@keyframes spinOrbit {
  from { transform: rotate(0deg); }
  to   { transform: rotate(360deg); }
}

.inspector-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 14px;
  border-bottom: 1px solid rgba(148, 163, 184, 0.2);
  padding-bottom: 14px;
  margin-bottom: 18px;
}

.el-big-badge {
  display: flex;
  align-items: center;
  gap: 16px;
}

.el-symbol-box {
  width: 68px;
  height: 68px;
  border-radius: 16px;
  background: linear-gradient(135deg, var(--accent), var(--secondary));
  display: grid;
  place-items: center;
  font-size: 2rem;
  font-weight: 900;
  color: white;
  box-shadow: var(--glow);
}

.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 11px;
  margin-bottom: 16px;
}

.metric-card {
  background: rgba(30, 41, 59, 0.75);
  border: 1px solid rgba(148, 163, 184, 0.18);
  padding: 10px 13px;
  border-radius: 12px;
}

.metric-card .m-label {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #94a3b8;
  display: block;
}

.metric-card .m-val {
  font-size: 0.98rem;
  font-weight: 700;
  color: #f1f5f9;
  font-family: 'JetBrains Mono', Consolas, monospace;
}

/* Diagramme de cases quantiques (Aufbau / Hund / Pauli) */
.orbital-diagram {
  background: rgba(9, 13, 22, 0.68);
  border: 1px solid rgba(99, 102, 241, 0.25);
  border-radius: 12px;
  padding: 14px 16px;
  margin-top: 12px;
}

.orbital-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 10px;
}

.subshell-group {
  background: rgba(30, 41, 59, 0.92);
  border: 1px solid rgba(99, 102, 241, 0.32);
  border-radius: 8px;
  padding: 6px 9px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.subshell-title {
  font-size: 0.72rem;
  font-weight: 700;
  color: #a5b4fc;
  margin-bottom: 4px;
  font-family: monospace;
}

.boxes-wrap {
  display: flex;
  gap: 4px;
}

.quantum-box {
  width: 26px;
  height: 26px;
  background: #0f172a;
  border: 1px solid #475569;
  border-radius: 5px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.78rem;
  color: #34d399;
  font-weight: 800;
  position: relative;
}

.quantum-box.unpaired {
  border-color: #34d399;
  box-shadow: inset 0 0 6px rgba(52, 211, 153, 0.25);
}

.quantum-box.paired {
  border-color: #818cf8;
  color: #a5b4fc;
}

/* Panneau API Wikipédia */
.wiki-panel {
  margin-top: 14px;
  background: rgba(15, 23, 42, 0.72);
  border: 1px solid rgba(148, 163, 184, 0.22);
  border-radius: 12px;
  padding: 14px 16px;
  display: flex;
  gap: 16px;
  align-items: flex-start;
}

.wiki-thumb {
  width: 84px;
  height: 84px;
  border-radius: 10px;
  object-fit: cover;
  border: 1px solid rgba(255, 255, 255, 0.18);
  flex-shrink: 0;
  background: #090d16;
  display: none;
}

.wiki-content {
  flex: 1;
  font-size: 0.88rem;
  color: #cbd5e1;
}

.wiki-link {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  margin-top: 6px;
  color: #818cf8;
  font-weight: 700;
  text-decoration: none;
  font-size: 0.82rem;
}
.wiki-link:hover { color: #c7d2fe; text-decoration: underline; }

/* Sections et Cartes */
section { padding: 48px 0; }

.section-title {
  font-size: clamp(1.5rem, 2.5vw, 2.05rem);
  margin: 0 0 24px;
  font-weight: 800;
  background: linear-gradient(135deg, #a5b4fc 0%, #f472b6 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  backdrop-filter: blur(10px);
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--accent), var(--secondary), var(--tertiary));
  opacity: 0;
  transition: opacity 0.3s ease;
}

.card:hover::before { opacity: 1; }
.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(99, 102, 241, 0.35);
}

.card .head {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.09) 0%, rgba(236, 72, 153, 0.06) 100%);
  padding: 18px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  border-bottom: 1px solid var(--border);
}

.card .head h3 {
  margin: 0;
  font-size: 1.12rem;
  color: var(--text-dark);
  font-weight: 800;
}

.badge {
  font-size: 0.73rem;
  padding: 5px 11px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), var(--accent-glow));
  color: white;
  font-weight: 700;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  white-space: nowrap;
}

.card .body { padding: 20px; }
.card ul { margin: 0; padding-left: 20px; }
.card li { margin: 8px 0; color: var(--text-muted); font-size: 0.94rem; }
.card li strong { color: var(--text-dark); font-weight: 700; }

.equation-pill {
  background: #0f172a;
  color: #a7f3d0;
  font-family: 'JetBrains Mono', Consolas, monospace;
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 0.85rem;
  margin: 12px 0;
  display: block;
  overflow-x: auto;
}

/* Graphe des tendances périodiques */
.trends-panel {
  background: rgba(15, 23, 42, 0.9);
  border: 1px solid rgba(99, 102, 241, 0.3);
  border-radius: var(--radius);
  padding: 24px;
  color: white;
  box-shadow: var(--shadow-lg);
}

#trendsCanvas {
  width: 100%;
  height: 300px;
  background: #090d16;
  border-radius: 12px;
  border: 1px solid rgba(148, 163, 184, 0.2);
  margin-top: 14px;
  display: block;
}

/* Footer */
footer {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: rgba(255, 255, 255, 0.85);
  padding: 32px 0;
  margin-top: 60px;
}

footer .row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

footer a {
  color: var(--accent-light);
  font-weight: 600;
  text-decoration: none;
  transition: color 0.3s ease;
}
footer a:hover { color: white; }

/* Bouton Retour en haut */
#toTop {
  position: fixed;
  right: 24px;
  bottom: 24px;
  width: 54px;
  height: 54px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  border: none;
  background: linear-gradient(135deg, var(--accent), var(--accent-glow));
  box-shadow: var(--shadow), var(--glow);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px) scale(0.8);
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  color: white;
  z-index: 90;
}

#toTop.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

#toTop:hover {
  transform: translateY(-4px) scale(1.06);
  box-shadow: var(--shadow-lg), 0 0 30px rgba(99, 102, 241, 0.65);
}

#toTop svg { width: 24px; height: 24px; }