<!DOCTYPE html>
Passes if no red.
<div style="width: 300px; height: 300px; background: green; outline: 1px solid green; position: absolute; z-index: 1"></div>
<div style="width: 300px; height: 300px; overflow: hidden">
<div style="transform: rotate(45deg); width: 300px; height: 300px">
<div style="opacity: 0.9">
<div style="position: fixed; will-change: transform; width: 300px; height: 300px; background: red"></div>
</div>
</div>
</div>