<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>
document.addEventListener('DOMContentLoaded', () => {
  const form = document.createElement("form");
  const range = new Range();
  document.documentElement.contentEditable = true;
  document.execCommand("formatBlock", false, "h3");
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  range.setStartBefore(form);
  getSelection().addRange(range);
  range.selectNode(form);
  document.execCommand("insertHorizontalRule");
});
</script>
</head>
</html>
