/* back-to-top.css — cf. components/composants-communs.md §3 */

.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: var(--z-back-to-top);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border: none;
  border-radius: var(--radius-full);
  background: var(--color-black);
  color: var(--color-gold-light);
  /* Anneau or fin autour de la pastille noire - rappel des cercles du logo */
  box-shadow: inset 0 0 0 1px rgba(201, 160, 92, 0.45), var(--shadow-md);
  opacity: 0;
  transform: translateY(8px) scale(0.9);
  pointer-events: none;
  transition: opacity var(--transition-slow) var(--easing-luxe),
              transform var(--transition-slow) var(--easing-luxe),
              box-shadow var(--transition-slow) var(--easing-luxe);
}

.back-to-top.is-visible {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.back-to-top:hover,
.back-to-top:focus-visible {
  box-shadow: inset 0 0 0 1px rgba(217, 179, 106, 0.85), 0 12px 28px rgba(176, 141, 87, 0.35);
  transform: translateY(-3px) scale(1);
}

@media (prefers-reduced-motion: reduce) {
  .back-to-top {
    transform: none;
  }

  .back-to-top:hover,
  .back-to-top:focus-visible {
    transform: none;
  }
}

.back-to-top svg {
  width: 18px;
  height: 18px;
}