style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body{
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: rgb(0, 0, 0);
}

.cube{
    position: relative;
    width: 300px;
    height: 300px;
    transform-style: preserve-3d;
    transform: rotateX(-30deg);
    animation: animate 4s linear infinite;
}

@keyframes animate{
    0%{
        transform: rotateX(-30deg) rotateY(0deg);
    }
    100%{
        transform: rotateX(-30deg) rotateY(360deg);
    }
}

.cube div{
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
}

.cube div span{
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(rgb(0, 0, 0), rgba(130, 40, 180, 0.8));
    transform: rotateY(calc(90deg *var(--i))) translateZ(150px);
}

.top{
    position: absolute;
    top: 0;
    left: 0;
    width: 300px;
    height: 300px;
    background: rgb(30, 30, 30);
    transform: rotateX(90deg) translateZ(149px);
}

.top::before{
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 300px;
    height: 300px;
    background-color: rgb(150, 50, 200);
    transform: translateZ(-380px);
    filter: blur(20px);
    box-shadow: 0 0 120px rgba(150, 50, 200, 0.2),
    0 0 200px rgba(150, 50, 200, 0.4),
    0 0 300px rgba(150, 50, 200, 0.6),
    0 0 400px rgba(150, 50, 200, 0.8),
    0 0 500px rgba(150, 50, 200, 1);
}