medium-text-bg-animation-demo

style.css

body {
  background-color: #2b2c34;
}

.animated-text {
  font-family: "VT323", monospace, sans-serif;
  text-shadow: 0 0 1px #ffffff;
  position: fixed;
  bottom: -100vh;
  user-select: none;
  animation-name: float-animation;
  animation-timing-function: ease-in-out;
  z-index: -1;
}

@keyframes float-animation {
  0% {
    top: 100vh;
    opacity: 0;
  }
  25% {
    opacity: 1;
  }
  50% {
    opacity: 1;
  }
  75% {
    opacity: 0.75;
  }
  100% {
    top: 0;
    opacity: 0;
  }
}