<html>
<body>
  <template>
    <p>template content</p>
  </template>
  <div></div>
  <script>
    "use strict";

    const template = document.querySelector("template");
    const clone = document.importNode(template.content, true);
    document.querySelector("div").appendChild(clone);

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