css/css-ruby/root-block-ruby.xhtml

<!DOCTYPE html>
<!--
     Any copyright is dedicated to the Public Domain.
     http://creativecommons.org/publicdomain/zero/1.0/
  -->
<html lang="ja" xmlns="http://www.w3.org/1999/xhtml">
<meta charset="utf-8"/>
<title>CSS Ruby Test: :root element with 'display:block ruby'.</title>
<link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com"/>
<link rel="help" href="https://drafts.csswg.org/css-display/#propdef-display"/>
<link rel="help" href="https://drafts.csswg.org/css-ruby-1/#box-fixup"/>
<link rel="help" href="https://drafts.csswg.org/css-display-3/#inlinify"/>
<link rel="match" href="root-ruby-ref.xhtml"/>
<style>
:root { display: block ruby; }
rbc {
  display: ruby-base-container;
}
rtc {
  display: ruby-text-container;
}
</style>
べ
<rtc>
  <rt>る</rt>
</rtc>
<rbc>
  <rb>A</rb>
  <rb>B</rb>
</rbc>

<pre></pre>
<script>
let ruby = Array.prototype.slice.call(document.querySelectorAll(':root'));
let result = ruby.map(e => window.getComputedStyle(e).display + ', ').reduce((s, t) => s + t, "");
document.querySelector('pre').appendChild(document.createTextNode(result));
</script>
</html>