html {
  height: 100%;
  display: grid;
}

body{margin:0;padding:0;}

#space {
  background-color: black;
  position: relative;
  width: 100%;
  height: 100%;
  display: grid;
  place-items: center center;
  overflow: hidden;
  --perspective: 100px;
  -webkit-perspective: var(--perspective);
          perspective: var(--perspective);
  -webkit-transform-style: preserve-3d;
          transform-style: preserve-3d;
}
#space:after {
  display: block;
  content: '';
  grid-area: 1 / 1;
  width: 100%;
  height: 100%;
  background-image: linear-gradient(45deg, blue, transparent, yellow), linear-gradient(to right, #008aff, transparent, #e10019), linear-gradient(to bottom, green, cyan, purple);
  mix-blend-mode: overlay;
}

#space time {
  grid-area: 1 / 1;
  width: 100px;
  height: 100px;
  -webkit-transform-origin: 50% 0%;
          transform-origin: 50% 0%;
  will-change: transform;
  background-color: white;
  box-shadow: 0 0 .5rem white, 0 0 1rem white;
}
@supports (-moz-transition: all) {
  #space time {
    box-shadow: 0 0 .5rem white;
  }
}