chromium/third_party/blink/web_tests/external/wpt/css/css-will-change/will-change-abspos-cb-003.html

<!doctype html>
<meta charset="utf-8">
<title>CSS Test: will-change: backdrop-filter should generate a containing block for absolute positioned elements.</title>
<link rel="author" title="Philip Rogers" href="mailto:[email protected]">
<link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=960953">
<link rel="help" href="https://drafts.csswg.org/css-will-change/#will-change">
<link rel="help" href="https://drafts.fxtf.org/filter-effects-2/#BackdropFilterProperty">
<link rel="match" href="will-change-abspos-cb-003-ref.html">
<style>
  .container {
    border: 1px solid green;
    background: red;
    width: 100px;
    height: 100px;
    margin-top: 100px;
    will-change: backdrop-filter;
  }
  .abspos {
    position: absolute;
    top: 0;
    left: 0;
    background: green;
    height: 100px;
    width: 100px;
  }
</style>
<div class="container">
  <div class="abspos"></div>
</div>