<!DOCTYPE html>
<style>
  div {
    aspect-ratio: 1;
    mask-image: url(http://localhost:8000);
  }
  ol {
    column-span: all;
  }
  ol:only-child {
    column-count: 2;
  }
  :nth-child(2) {
    content: url();
  }
</style>
<script>
  onload = () => {
    document.documentElement.append(document.createElement('div'));
    document.designMode = 'on';
    document.execCommand('SelectAll');
    for (let i = 0; i < 10; i++) { 
      document.execCommand('InsertNestedOrderedList');
    }
    if (window.testRunner)
      testRunner.dumpAsText();
    console.log("This test passes if it does not crash.");
  };
</script>