.livre1 {
  opacity: 0;
  transform: translateY(40px) scale(0.98); /* descend + léger zoom out */
  transition: opacity 2s ease, transform 1s ease; /* plus long et fluide */
  will-change: opacity, transform; /* optimise pour les animations */
}

.livre1.show {
  opacity: 2;
  transform: translateY(0) scale(1);
}