LayoutTests/fast/ruby/ruby-block-style-propagation.html

<style>
div {
  display: flex;
}
ruby {
  ruby-position: over;
}
</style>
<div><ruby id=foobar>base<rt>annotation</rt></ruby></div>
PASS if annotation is below base.
<script>
document.body.offsetHeight;
foobar.style.rubyPosition = "under";
</script>