css/css-multicol/multicol-fill-balance-022.html

<!DOCTYPE html>
<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
<link rel="help" href="https://www.w3.org/TR/css-multicol-1/#cf">
<link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1308024">
<div id="outer" style="columns:2;">
  <div id="inner" style="columns:2; border-top:solid 3px;">
    <div style="height:97px; contain:size;"></div>
  </div>
</div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
  test(()=> {
    assert_equals(outer.offsetHeight, 100);
  }, "Nested balancing outer height");
  test(()=> {
    assert_equals(inner.offsetHeight, 100);
  }, "Nested balancing inner height");
</script>