.js-slidein {
  opacity: 0;
}

.come-in {
  transform: translateY(150px);
  animation: come-in 0.8s ease forwards;
  opacity: 1;
}
.come-in:nth-child(odd) {
  animation-duration: 0.6s;
}
.already-visible {
  transform: translateY(0);
  animation: none;
}

@keyframes come-in {
  to { transform: translateY(0); }
}