<style>
  html::first-letter {
    width: 0;
  }
</style>
<script>
  if (window.testRunner)
    testRunner.dumpAsText();
  onload = () => {
    document.execCommand('SelectAll');
    document.body.append('aa');
    document.documentElement.append('');
    document.body.offsetTop;
    document.body.style.overflow = 'clip';
  };
</script>