chromium/third_party/blink/web_tests/fast/lists/nested-list-quirks-marker.html

<style>
::marker {
  content: "[marker]";
}
</style>

<ul>
  <li>
    <ol>
      <li>item</li>
      <li>item</li>
    </ol>
  </li>
</ul>

<ol>
  <li>
    <ol>
      <li>item</li>
      <li>item</li>
    </ol>
  </li>
</ol>