@keyframes fadeIn {
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }
  
  .fleche-haut {
    position: sticky;
    top: 50vh;
    display: block;
    margin: 1px 0 0 auto;
    width: max-content;
  
    text-decoration: none;
    opacity: 0;
    transform: translateY(-10px);
    animation: fadeIn 0.6s ease-out 1.4s forwards;
    z-index: 1000;
  
    padding: 8px 12px;
    background: var(--bleu-acier);
    color: var(--blanc-pur);
    border-radius: 8px 0 0 8px;
  }
  
  /* Effet au survol (desktop) */
  .fleche-haut:hover {
    transform: translateY(-12px) scale(1.02);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
    background: var(--bleu-gris, var(--bleu-ardoise-fonce));
    border: 2px solid var(--bleu-clair);
  }