:root{
  --rotateSpeed: 1s;
}
body{
  background-color: #000;
  display: flex;
  justify-content: center;
}
.floor{
  align-self: center;
  transform: 
    translate(-50%, -50%)
    rotateX(98deg);
  animation: sceneRotate var(--rotateSpeed) infinite linear;
  width: 500px;
  height: 500px;
  background-image: 
    radial-gradient(#0000, #000 75%),
    repeating-conic-gradient(
      from 45deg,
      #111 0deg 90deg,
      #222 98deg 180deg);
  background-size: 100%, 2em 2em;
}
@keyframes sceneRotate {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}