body {
    font-size: 12px;
    perspective: 500px;
    overflow: hidden;
    margin: 0;
    background-color: white;}
#app {
    width: 100vw;
    height: 100vh;
    transform-style: preserve-3d;
    animation: rot 5s linear infinite normal;}
#app div {
    position: absolute;
    left: 50%;
    top: 50%;
    width: 20px; 
    height: 20px;
    background-size: cover; 
    transform-origin: 0 0;}
@keyframes rot {
    to { transform: rotateY(1turn); }}