css/motion/offset-path-shape-circle-001-ref.html

<!doctype html>
<meta charset="utf-8">
<title>CSS Motion Path test reference: &lt;basic-shape&gt; circle() path with explicit arguments</title>
<link rel="author" title="Daniil Sakhapov" href="sakhapov@google.com">

<style>
#outer {
  top: 100px;
  left: 100px;
  position: relative;
  width: 600px;
  height: 400px;
}
#box {
  background-color: green;
  transform: translate(250px, 350px) rotate(180deg);
  border-radius: 50% 50% 0 0;
  width: 100px;
  height: 100px;
}
</style>

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