.nieve {
  position: fixed;
  top: -10px;
  z-index: 999999;
  color: white;
  user-select: none;
  pointer-events: none;
  font-size: 18px;
  animation-name: caer;
  animation-timing-function: linear;
}
@keyframes caer {
  0% { transform: translateY(0); opacity: 1; }
  100% { transform: translateY(110vh); opacity: 0; }
}