chromium/third_party/blink/web_tests/fast/frames/frameset-border-inheritance.html

<!DOCTYPE html>
<html class="reftest-wait">
<script>
window.onload = () => {
  requestAnimationFrame(() => requestAnimationFrame(() => {
    document.body.removeAttribute('border');
    document.documentElement.removeAttribute('class');
  }));
};
</script>
<frameset border="20" cols="40%,*">
  <frameset rows="60%,*">
    <frame></frame>
    <frame></frame>
  </frameset>
  <frame></frame>
</frameset>
</html>