<html>
<head>
<body>
    <div id="relative_parent" style="position: relative">
        <div id="absolute_child" style="position: absolute"></div>
    </div>
    <div id="static"></div>
    <div id="no_parent" style="position: absolute"></div>
    <div id="fixed" style="position: fixed"></div>
    <script>
       "use strict";

       window.onload = () => {
         window.opener.postMessage("ready", "*");
       };
     </script>
</body>
</html>
