html {
  height: 100%;
  width: 100%;
}

body {
  background-color: darkgrey;
  width: 100vw;
  height: 100vh;
}

div {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  width: 100vw;
  color: gold;
  font-family: 'Courier New', Courier, monospace;
  font-size: 72px;
  animation-name: example;
  animation-duration: 2s;
}

@keyframes example {
  0% {
    opacity: 1;
  }

  50% {
    opacity: 0;
  }

  100% {
    opacity: 1;
  }
}