chromium/third_party/blink/web_tests/external/wpt/css/motion/offset-path-shape-polygon-001.html

<!doctype html>
<meta charset="utf-8">
<title>CSS Motion Path test: &lt;basic-shape&gt; polygon() path</title>
<link rel="author" title="Daniil Sakhapov" href="[email protected]">
<link rel="match" href="offset-path-shape-polygon-001-ref.html">
<link rel="help" href="https://drafts.fxtf.org/motion/#valdef-offset-path-basic-shape">
<meta name="fuzzy" content="maxDifference=0-20; totalPixels=0-100">

<style>
#outer {
  top: 100px;
  left: 100px;
  position: relative;
  width: 600px;
  height: 400px;
}
#box {
  background-color: green;
  position: relative;
  offset-path: polygon(0px 0px, 600px 0px, 300px 400px);
  offset-distance: 90%;
  width: 100px;
  height: 100px;
}
</style>

<div id="outer">
  <div id="box"></div>
</div>