third_party/blink/web_tests/transforms/perspective-fixed-pos-descendant.html - chromium/src - Git at Google

 <!DOCTYPE html>
 <div style="width:100px; height:100px; perspective:100px; background:red;">
   <div style="position:fixed; left:25px; top:25px; width:50px; height:50px; transform:translateZ(50px); background:green;"></div>
 </div>
 This test verifies CSS perspective correctly applies to fixed-position descendants. The test passes if a 100x100 green box completely occludes the red box behind.
	<!DOCTYPE html>
	<div style="width:100px; height:100px; perspective:100px; background:red;">
	<div style="position:fixed; left:25px; top:25px; width:50px; height:50px; transform:translateZ(50px); background:green;"></div>
	</div>
	This test verifies CSS perspective correctly applies to fixed-position descendants. The test passes if a 100x100 green box completely occludes the red box behind.