<!DOCTYPE html>
<html>
<head>
    <script>
      window.addEventListener('load', () => {
        document.execCommand('selectAll', false, null)
        document.execCommand('formatBlock', false, 'h1')
      })
    </script>
</head>
<body>
<main contenteditable='true'>
    <li></li>
    <ol contenteditable='false'>
    </ol>
</main>
</body>
</html>
