@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes fadeOut {
  from { opacity: 1; }
  to { opacity: 0; }
}

.fade-in {
  animation: fadeIn var(--time, 1000ms) ease-in-out forwards;
}

.fade-out {
  animation: fadeOut var(--time, 1000ms) ease-in-out forwards;
}