.cube-red {
    position: absolute;
    top: 120px;
    width: 75px;
    height: 75px;
    transform-style: preserve-3d;
    transform: rotateX(-30deg);
    animation: animate 10s linear infinite;
    z-index: 30;
}
@keyframes animate {
    0% {
        transform: rotateX(-30deg) rotateY(0deg);
    }
    100% {
        transform: rotateX(-30deg) rotateY(360deg);
    }
}
.cube-red div {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
}
.cube-red div span {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(#151515, #ec0000);
    transform: rotateY(calc(90deg * var(--i))) translateZ(37.5px);
}

.top-cube-red {
    position: absolute;
    top: 0;
    left: 0;
    width: 75px;
    height: 75px;
    background: #222;
    transform: rotateX(90deg) translateZ(37.5px);
}
.top-cube-red::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 75px;
    height: 75px;
    background: #f00;
    transform: translateZ(-75px);
    filter: blur(20px);
    box-shadow: 0 0 120px rgba(255, 0, 0, 0.2),
    0 0 50px rgba(255, 0, 0, 0.4),
    0 0 75px rgba(255, 0, 0, 0.6),
    0 0 100px rgba(255, 0, 0, 0.8),
    0 0 125px rgba(255, 0, 0, 0.10);
}