.cube {
  position: relative;
  width: 300px;
  height: 300px;
  transform-style: preserve-3d;
  transform: rotateX(-30deg);
  animation: animateD 8s linear infinite;
}

@keyframes animateD {
  0% {
    transform: rotateX(-15deg) rotateY(0deg);
  }

  100% {
    transform: rotateX(-15deg) rotateY(-360deg);
  }
}

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

.cube2 {
  position: relative;
  width: 150px;
  height: 150px;
  transform-style: preserve-3d;
  animation: animateD2 5s ease-out infinite alternate;
}

@keyframes animateD2 {
  0% {
    transform: rotateX(0deg) rotateY(0deg);
  }

  100% {
    transform: rotateX(180deg) rotateY(-360deg);
  }
}

.cube2 div {
  position: absolute;
  top: 35px;
  left: 0;
  width: 65%;
  height: 65%;
  transform-style: preserve-3d;
}

.cube2 div span {
  position: absolute;
  top: 20%;
  left: 20%;
  width: 65%;
  height: 65%;
  background: transparent;
  border: 2px solid #7dff99;
  transform: rotateY(calc(90deg * var(--i))) translateZ(62px);
}

.cube3 {
  position: absolute;
  width: 300px;
  height: 300px;
  transform-style: preserve-3d;
  transform: rotateX(-30deg);
  animation: animateD3 1s ease-in-out infinite alternate;
}

@keyframes animateD3 {
  0% {
    transform: rotateX(-90deg) rotateY(0deg);
  }

  100% {
    transform: rotateX(90deg) rotateY(45deg);
  }
}

.cube3 div {
  position: absolute;
  top: 70px;
  left: 70px;
  width: 15%;
  height: 15%;
  transform-style: preserve-3d;
}

.cube3 div span {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: #7dff99;
  transform: rotateY(calc(90deg * var(--i))) translateZ(14px);
  box-shadow: 0px 0px 7px #7dff99;
}

.top3 {
  position: absolute;
  top: 0;
  left: 0;
  background: #7dff99;
  transform: rotateX(90deg) translateZ(14px);
  box-shadow: 0px 0px 10px #7dff99;
}