/* ==========================================================================
   Tribu Roadtrip 2027 — layout.css
   Header, navigation, héros, sections, grilles, footer, bouton retour en haut
   ========================================================================== */

/* --- HEADER STICKY AVEC EFFET 3D PSYCHÉDÉLIQUE --- */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  background: rgba(6, 4, 15, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 2px solid transparent;
  border-image: linear-gradient(90deg, #7b2cbf 0%, #e024c3 25%, #4cc9f0 50%, #f72585 75%, #7b2cbf 100%) 1;
  box-shadow: 0 10px 30px -10px rgba(123, 44, 191, 0.45), 0 2px 15px rgba(224, 36, 195, 0.2);
  z-index: 100;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  transform: translateZ(0);
}

.site-header:hover {
  box-shadow: 0 12px 35px -8px rgba(157, 78, 221, 0.6), 0 4px 25px rgba(247, 37, 133, 0.35);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
  width: 100%;
  max-width: 100%;
  padding-left: clamp(1rem, 2.5vw, 2.5rem);
  padding-right: clamp(1rem, 2.5vw, 2.5rem);
  flex-wrap: nowrap;
  white-space: nowrap;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text);
  flex-shrink: 0;
  white-space: nowrap;
}

.header-logo {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  object-fit: contain;
  flex-shrink: 0;
  filter: drop-shadow(0 0 10px rgba(224, 36, 195, 0.6));
  transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1), filter 0.4s ease;
}

.brand-link:hover .header-logo {
  transform: scale(1.1) rotate(8deg);
  filter: drop-shadow(0 0 18px rgba(199, 125, 255, 0.9)) drop-shadow(0 0 8px #f72585);
}

.brand-text {
  display: flex;
  flex-direction: column;
  white-space: nowrap;
}

.brand-name {
  font-size: 1.15rem;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: #ffffff;
  white-space: nowrap;
}

.brand-tagline {
  font-size: 0.75rem;
  color: var(--violet-light);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  white-space: nowrap;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
  white-space: nowrap;
  margin-left: auto;
}

/* Sur mobile et tablette (< 1024px) : LOGO, TITRE/SOUS-TITRE COMPACTS ET BURGER */
@media (max-width: 1023px) {
  .header-container {
    height: 64px;
    padding-left: 0.75rem;
    padding-right: 0.75rem;
  }
  .brand-link {
    gap: 0.5rem;
    max-width: calc(100% - 60px);
  }
  .brand-text {
    display: flex !important;
    flex-direction: column;
    justify-content: center;
    line-height: 1.15;
  }
  .brand-name {
    font-size: 0.95rem;
    letter-spacing: 0.3px;
  }
  .brand-tagline {
    font-size: 0.68rem;
    letter-spacing: 0.5px;
  }
  .site-nav {
    display: none !important;
  }
  .header-actions .btn {
    display: none !important;
  }
  .header-logo {
    width: 40px;
    height: 40px;
  }
  .nav-toggle {
    display: flex !important;
    width: 42px;
    height: 42px;
  }
}

/* Navigation Desktop : masquée par défaut sur mobile, affichée uniquement à partir de 1024px */
.site-nav {
  display: none;
}

@media (min-width: 1024px) {
  .site-nav {
    display: flex;
    align-items: center;
    gap: 1.25rem;
    margin-left: auto;
    margin-right: 2rem;
  }
}

.nav-list {
  display: flex;
  list-style: none;
  gap: 1rem;
  align-items: center;
}

.nav-link {
  position: relative;
  display: inline-block;
  color: var(--text-soft);
  text-decoration: none !important;
  border-bottom: none !important;
  font-size: 0.95rem;
  font-weight: 700;
  padding: 0.45rem 0.85rem;
  border-radius: 6px;
  transition: color 0.25s ease, transform 0.25s ease, text-shadow 0.25s ease;
  z-index: 1;
}

/* Effet de coup de brush artistique multicolore (Colorful Brush Stroke) - CONSERVÉ */
.nav-link::before {
  content: "";
  position: absolute;
  inset: 10% -6px 8% -6px;
  background: linear-gradient(110deg, #ff007f 0%, #e024c3 22%, #9d4edd 48%, #00f0ff 78%, #ffbe0b 100%);
  background-size: 220% 100%;
  border-radius: 255px 25px 225px 25px / 25px 225px 25px 255px;
  transform: scaleX(0) skewX(-14deg) rotate(-1.5deg);
  transform-origin: left center;
  transition: transform 0.35s cubic-bezier(0.2, 0.9, 0.3, 1.2), opacity 0.25s ease, background-position 0.6s ease;
  opacity: 0;
  z-index: -1;
  filter: drop-shadow(0 2px 10px rgba(224, 36, 195, 0.6));
  pointer-events: none;
}

/* Retrait du soulignement sur hover (demandé expressément : coup de brush sans soulignement) */
.nav-link::after {
  display: none !important;
}

.nav-link:hover, .nav-link:focus-visible {
  color: #ffffff;
  text-decoration: none !important;
  border-bottom: none !important;
  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.9);
}

.nav-link:hover::before, .nav-link:focus-visible::before {
  transform: scaleX(1) skewX(-10deg) rotate(-1.2deg);
  opacity: 0.95;
  background-position: right center;
}

.nav-link.active {
  color: #ffffff;
  text-decoration: none !important;
  border-bottom: none !important;
  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.8);
}

.nav-link.active::before {
  transform: scaleX(1) skewX(-8deg) rotate(-1deg);
  opacity: 0.85;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Bouton Hamburger accessible (visible sur smartphone et tablette < 1024px) */
.nav-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  padding: 8px;
  touch-action: manipulation;
  z-index: 101;
}

@media (min-width: 1024px) {
  .nav-toggle {
    display: none !important;
  }
}

.nav-toggle-bar {
  width: 22px;
  height: 2px;
  background-color: var(--text);
  border-radius: 2px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* Tiroir Mobile avec effet 3D psychédélique */
.mobile-nav-drawer {
  position: fixed;
  top: 64px;
  left: 0;
  width: 100%;
  height: calc(100vh - 64px);
  background: linear-gradient(180deg, rgba(14, 10, 31, 0.96) 0%, rgba(22, 16, 51, 0.98) 100%);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-top: 2px solid transparent;
  border-image: linear-gradient(90deg, #e024c3, #7b2cbf, #4cc9f0) 1;
  box-shadow: inset 0 0 40px rgba(123, 44, 191, 0.35), 0 20px 50px rgba(0, 0, 0, 0.9);
  padding: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  overflow-y: auto;
  transform: perspective(800px) rotateX(-15deg) translateY(-20px);
  opacity: 0;
  pointer-events: none;
  transform-origin: top center;
  transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.35s ease;
  z-index: 99;
}

.mobile-nav-drawer.open {
  transform: perspective(800px) rotateX(0deg) translateY(0);
  opacity: 1;
  pointer-events: auto;
}

.mobile-nav-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.mobile-nav-link {
  position: relative;
  display: block;
  padding: 0.9rem 1.35rem;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none !important;
  border-radius: 10px;
  background: rgba(22, 16, 51, 0.65);
  border: 1px solid rgba(123, 44, 191, 0.3);
  transition: color 0.25s ease, transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
  overflow: hidden;
  z-index: 1;
}

/* Effet de coup de brush artistique multicolore (Colorful Brush Stroke) version Mobile */
.mobile-nav-link::before {
  content: "";
  position: absolute;
  inset: -10% -12px -10% -12px;
  background: linear-gradient(110deg, #ff007f 0%, #e024c3 22%, #9d4edd 48%, #00f0ff 78%, #ffbe0b 100%);
  background-size: 220% 100%;
  border-radius: 255px 25px 225px 25px / 25px 225px 25px 255px;
  transform: scaleX(0) skewX(-14deg) rotate(-1.5deg);
  transform-origin: left center;
  transition: transform 0.35s cubic-bezier(0.2, 0.9, 0.3, 1.2), opacity 0.25s ease, background-position 0.6s ease;
  opacity: 0;
  z-index: -1;
  filter: drop-shadow(0 4px 16px rgba(224, 36, 195, 0.65));
  pointer-events: none;
}

.mobile-nav-link:hover, .mobile-nav-link:focus-visible, .mobile-nav-link:active {
  color: #ffffff;
  border-color: rgba(255, 0, 127, 0.7);
  transform: translateX(8px);
  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.9);
  box-shadow: 0 6px 20px rgba(224, 36, 195, 0.45);
}

.mobile-nav-link:hover::before, .mobile-nav-link:focus-visible::before, .mobile-nav-link:active::before {
  transform: scaleX(1) skewX(-6deg) rotate(-0.5deg);
  opacity: 0.96;
  background-position: right center;
}

/* --- SECTION HÉROS --- */
.hero-section {
  position: relative;
  min-height: 82vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-5) 0;
  overflow: hidden;
}

/* --- VIDÉO D'AMBIANCE HÉROS --- */
.hero-video-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  z-index: 0;
  pointer-events: none;
}

.hero-video-wrapper {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 100vw;
  height: 56.25vw;
  min-height: 100%;
  min-width: 177.77vh;
  pointer-events: none;
}

.hero-video-poster {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
}

.hero-poster-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.hero-video-wrapper iframe {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  border: 0;
  pointer-events: none;
  filter: contrast(1.05) saturate(1.1);
  opacity: 0;
  transition: opacity 0.8s ease-in-out;
}

.hero-video-wrapper iframe.loaded {
  opacity: 1;
}

.hero-video-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(180deg, 
    rgba(6, 4, 15, 0.65) 0%, 
    rgba(6, 4, 15, 0.72) 35%, 
    rgba(6, 4, 15, 0.85) 75%, 
    rgba(3, 2, 8, 0.96) 95%, 
    #030208 100%);
  z-index: 1;
  pointer-events: none;
}

/* Reflet doux et diffus au bas de la vidéo pour transition fluide */
.hero-video-reflection {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 150px;
  background: radial-gradient(ellipse at 50% 100%, rgba(224, 36, 195, 0.22) 0%, rgba(123, 44, 191, 0.16) 40%, transparent 75%);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  z-index: 2;
  pointer-events: none;
}

/* Base des triangles en .svg au bas du héros au pixel près */
.hero-video-triangles-base {
  position: absolute;
  bottom: 0px;
  left: 0;
  width: 100%;
  height: 55px;
  z-index: 3;
  pointer-events: none;
  line-height: 0;
  margin: 0;
  padding: 0;
}

.hero-video-triangles-base svg {
  display: block;
  width: 100%;
  height: 100%;
  vertical-align: bottom;
}

/* Décor Triangles cosmiques du héros — COLLÉS TOUT EN BAS DE LA VIDÉO */
.hero-triangles-decor {
  position: absolute;
  bottom: 0px;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 1300px;
  height: 100%;
  pointer-events: none;
  z-index: 2;
  opacity: 0.75;
}

/* Enlever les triangles en mode smartphone ou petite résolution */
@media (max-width: 768px) {
  .hero-triangles-decor {
    display: none !important;
  }
  .hero-video-triangles-base {
    display: none !important;
  }
}

.hero-tri-shape {
  position: absolute;
  clip-path: polygon(50% 0%, 100% 100%, 0% 100%);
  filter: blur(1px) drop-shadow(0 0 30px rgba(224, 36, 195, 0.4));
}

.hero-tri-left {
  left: 3%;
  bottom: 0px;
  width: 380px;
  height: 440px;
  background: linear-gradient(180deg, rgba(114, 9, 183, 0.5) 0%, rgba(220, 38, 38, 0.25) 100%);
}

.hero-tri-center {
  left: 50%;
  bottom: 0px;
  transform: translateX(-50%);
  width: 520px;
  height: 580px;
  background: linear-gradient(180deg, rgba(224, 36, 195, 0.55) 0%, rgba(123, 44, 191, 0.25) 100%);
}

.hero-tri-right {
  right: 3%;
  bottom: 0px;
  width: 390px;
  height: 450px;
  background: linear-gradient(180deg, rgba(247, 37, 133, 0.5) 0%, rgba(114, 9, 183, 0.2) 100%);
}

.hero-content {
  position: relative;
  z-index: 4;
  text-align: center;
  max-width: 860px;
  margin: 0 auto;
  margin-bottom: 2.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: var(--space-2);
}

.hero-title {
  margin-top: var(--space-1);
  margin-bottom: var(--space-2);
  text-align: center;
  font-size: clamp(2.3rem, 5.5vw + 0.5rem, 3.8rem);
  text-shadow: 0 4px 24px rgba(0, 0, 0, 0.9), 0 0 35px rgba(123, 44, 191, 0.35);
}

.hero-subtitle {
  font-size: clamp(1.1rem, 2.3vw, 1.35rem);
  color: var(--text-soft);
  max-width: 740px;
  margin: 0 auto var(--space-3) auto;
  line-height: 1.5;
  text-align: center;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.9);
}

.hero-cta-group {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: var(--space-2);
}

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: var(--space-2);
}

.hero-title {
  margin-bottom: var(--space-2);
}

.hero-subtitle {
  font-size: clamp(1.1rem, 2.5vw, 1.35rem);
  color: var(--text-soft);
  max-width: 720px;
  margin: 0 auto var(--space-3) auto;
  line-height: 1.5;
}

.hero-cta-group {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
  margin-bottom: var(--space-2);
}

.hero-disclaimer {
  font-size: 0.85rem;
  color: var(--muted);
  font-style: italic;
  margin-bottom: var(--space-4);
}

.hero-visual-wrapper {
  margin: 0 auto;
  max-width: 1000px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  position: relative;
}

.hero-visual-img {
  width: 100%;
  height: auto;
  display: block;
}

/* --- BANDEAU BILLETTERIE BOOM --- */
.ticket-banner-section {
  padding: var(--space-3) 0;
  position: relative;
  z-index: 2;
}

/* --- SECTIONS GÉNÉRALES --- */
.section {
  padding: var(--space-4) 0;
  position: relative;
  scroll-margin-top: 80px;
}

/* Optimisation de rendu : ignorer le rendu DOM des sections hors de l'écran lors du chargement initial */
.section:not(.hero-section) {
  content-visibility: auto;
  contain-intrinsic-size: auto 650px;
}

@media (min-width: 768px) {
  .section {
    padding: var(--space-5) 0;
  }
}

.section-alt {
  background: rgba(14, 10, 31, 0.6);
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
}

.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto var(--space-4) auto;
}

.section-lead {
  font-size: 1.1rem;
  color: var(--text-soft);
}

/* --- GRILLES RESPONSIVES --- */
.grid {
  display: grid;
  gap: var(--space-3);
}

.grid-3 {
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .grid-3 {
    grid-template-columns: repeat(3, 1fr);
  }
}

.grid-4 {
  grid-template-columns: 1fr;
}

@media (min-width: 560px) {
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .grid-4 {
    grid-template-columns: repeat(4, 1fr);
  }
}

.grid-2 {
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .grid-2 {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Grille Séquence détails (texte + image agrandie) */
.seq-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4, 2rem);
  align-items: center;
  margin-top: var(--space-4, 2rem);
}

@media (min-width: 900px) {
  .seq-layout {
    grid-template-columns: 1fr 1.15fr;
    gap: 2.75rem;
  }
}

.seq-img-box {
  position: relative;
  display: block;
  width: 100%;
  border-radius: var(--radius-lg, 16px);
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: 0 14px 38px rgba(0, 0, 0, 0.55), 0 0 25px rgba(123, 44, 191, 0.2);
  background: var(--surface);
  cursor: zoom-in;
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), box-shadow 0.3s ease, border-color 0.3s ease;
}

.seq-img-box:hover {
  transform: translateY(-4px) scale(1.015);
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.7), 0 0 30px rgba(168, 85, 247, 0.35);
  border-color: rgba(168, 85, 247, 0.6);
}

.seq-img-box img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  display: block;
  transition: transform 0.5s ease;
}

.seq-img-box:hover img {
  transform: scale(1.03);
}

/* Badge indicatif 'Cliquer pour agrandir' sans émoji */
.seq-img-box::after {
  content: 'Agrandir en plein écran';
  position: absolute;
  bottom: 12px;
  right: 12px;
  background: rgba(15, 12, 29, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.3px;
  padding: 6px 14px;
  border-radius: 9999px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
  pointer-events: none;
  opacity: 0.9;
  transition: opacity 0.25s ease, transform 0.25s ease;
}

.seq-img-box:hover::after {
  opacity: 1;
  transform: scale(1.05);
  border-color: var(--magenta);
}

/* --- SECTION TALLY IFRAME --- */
.tally-container {
  margin-top: 2rem;
  text-align: center;
}

.tally-iframe-box {
  width: 100%;
  max-width: 800px;
  margin: 1.5rem auto 0 auto;
  min-height: 520px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.tally-iframe-box iframe {
  width: 100%;
  height: 600px;
  border: none;
}

/* --- FOOTER --- */
.site-footer {
  background: var(--bg);
  border-top: 1px solid var(--border);
  padding: var(--space-5) 0 var(--space-4) 0;
  margin-top: var(--space-5);
  font-size: 0.9rem;
}

.footer-top {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 1.5rem;
  margin-bottom: var(--space-4);
}

.footer-logo {
  width: 80px;
  height: 80px;
  border-radius: 50%;
}

.footer-non-affiliation {
  max-width: 600px;
  color: var(--muted);
  font-size: 0.85rem;
  line-height: 1.5;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1.5rem;
  list-style: none;
  margin: var(--space-2) 0;
}

.footer-bottom {
  text-align: center;
  border-top: 1px solid var(--border-soft);
  padding-top: var(--space-3);
  color: var(--muted);
  font-size: 0.85rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

.footer-credits {
  font-size: 0.95rem;
  color: var(--text-soft);
  margin: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.45rem;
  line-height: 1.5;
}

.footer-credits strong {
  color: #ffffff;
  font-weight: 700;
}

.footer-eco-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  color: #34d399;
  font-weight: 600;
  background: rgba(16, 185, 129, 0.12);
  border: 1px solid rgba(16, 185, 129, 0.35);
  padding: 0.15rem 0.65rem;
  border-radius: 9999px;
  font-size: 0.8rem;
  letter-spacing: 0.01em;
  transition: background 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

.footer-eco-badge:hover {
  background: rgba(16, 185, 129, 0.2);
  border-color: rgba(16, 185, 129, 0.6);
  transform: translateY(-1px);
}

.footer-copy {
  margin: 0;
  color: var(--muted);
  font-size: 0.8rem;
}

/* --- BOUTON RETOUR EN HAUT --- */
.back-to-top {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--surface-2);
  color: #ffffff;
  border: 1px solid var(--violet-neon);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 90;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.2s ease;
  box-shadow: var(--shadow);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-3px);
  background: var(--violet);
}

/* --- ANIMATION AU DÉFILEMENT (REVEAL) --- */
.reveal {
  opacity: 0;
  transform: translateY(20px) translateZ(0);
  transition: opacity 0.5s cubic-bezier(0.16, 1, 0.3, 1), transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
  will-change: opacity, transform;
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0) translateZ(0);
  will-change: auto;
}