chromium/third_party/blink/renderer/core/animation/test_data/transform-animation-update.html

<!DOCTYPE html>
<style>
@keyframes rotate {
  from {transform: rotateY(180deg);}
  to {transform: rotateY(0deg);}
}
#target {
  width: 100px;
  height: 100px;
  background: green;
  animation: rotate 9999s linear 0s infinite;
}
.backface-visible {
  backface-visibility: visible;
}
.backface-hidden {
  backface-visibility: hidden;
}
</style>
<div id="target" class="backface-visible"></div>