chromium/third_party/blink/web_tests/external/wpt/css/css-masking/clip/clip-no-stacking-context.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Clip does not create a stacking context</title>
<link rel="help" href="https://drafts.fxtf.org/css-masking-1/#propdef-clip">
<link rel="match" href="clip-no-stacking-context-ref.html">
<link rel="author" title="Philip Rogers" href="mailto:[email protected]">

<style>
  #bottom {
    position: absolute;
    width: 100px;
    height: 100px;
    background: red;
    z-index: 1;
  }
  #clip {
    position: absolute;
    clip: rect(0px, 100px, 100px, 0px);
  }
  #top {
    position: absolute;
    width: 100px;
    height: 100px;
    background: green;
    z-index: 3;
  }
</style>

<p>Expected: A green box with no red visible.</p>
<div id="bottom"></div>
<!-- If #clip creates a stacking context, it will be below #bottom (which has a
     higher z-index) which will force #top to be below #bottom as well. This
     should not happen because #clip should not create a stacking context. -->
<div id="clip">
  <div id="top"></div>
</div>