<!doctype html>
<html>
<head>
<script>
document.addEventListener("DOMContentLoaded", () => {
  getSelection().collapse(document.querySelector("content"), 1);
  document.querySelector("div[contenteditable]").addEventListener("DOMSubtreeModified", () => {
    document.querySelector("tr").replaceChild(
      document.querySelector("meter"),
      document.querySelector("th")
    );
  });
  document.execCommand("justifyFull");
});
</script>
</head>
<body>
<table>
<tr>
<th>
<div contenteditable>
<meter>
<content>
<ul></ul>
</div>
</th></tr></table>
</body>
</html>
