headingoffset-polyfill-body-top.test.html

<html>
  <body>
    <script src="./headingoffset-polyfill.js"></script>
    <div id="existing-container" headingoffset="1">
      <h1 id="existing-h1">Level 2</h1>
      <h2 id="existing-h2">Level 3</h2>
    </div>
    <div id="container"></div>
    <script type="module">
      import { runTests } from "@web/test-runner-mocha";
      import { tests } from "./headingoffset-polyfill.test.js";
      await runTests(tests);
    </script>
  </body>
</html>