<main>
  <div class="triangle"></div>
  <div class="triangle"></div>
</main>

main {
  perspective: 1000px;
  perspective-origin: 50% 50%;
}

@keyframes rot {
  from {
    transform: rotateX(0deg) rotateY(0deg);
  }
  to {
    transform: rotateX(360deg) rotateY(360deg);
  }
}

.triangle {
  background-color: #FF00FF;
  position: relative;
  clip-path: polygon(50% 0, 0 100%, 100% 100%);
  transition: transform 4s linear;
  transform-style: preserve-3d;
  animation: rot 8s infinite linear;
  overflow: hidden;
  position: absolute;
}

.triangle:nth-child(1) {
  top: 0;
  left: 50px;
  width: 100px;
  height: 100px;
}

.triangle:nth-child(2) {
  width: 150px;
  height: 150px;
  left: 300px;
  background-color: brown;
  background-image: repeating-linear-gradient(-45deg,
      transparent,
      transparent 20px,
      black 20px,
      black 40px);
}