<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS will-change reference</title>
<link rel="author" title="L. David Baron" href="https://dbaron.org/">
<link rel="author" title="Mozilla" href="http://www.mozilla.org/">
<style>
html, body { margin: 0; padding: 0; }
div { width: 100px; height: 100px; margin: 100px 0 0 100px; background: green }
</style>
<body>
  <div></div>
</body>