html,
body {
  height: 100%;
}

@keyframes float {
  0% {
    transform: translateY(100vh) scale(0);
    opacity: 0;
  }
  10% {
    opacity: 0.2;
  }
  90% {
    opacity: 0.2;
  }
  100% {
    transform: translateY(-100vh) scale(1);
    opacity: 0;
  }
}