<!DOCTYPE html>
<meta charset="utf-8">
<title>Test Reference</title>
<link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net">
<style>
.v-rl {
  writing-mode: vertical-rl;
  width: 200px;
}
span {
  display: inline-block;
  height: 1em;
}
#test { color: blue; }
#test2 { color: brown; }
#ref { color: orange; }
.v-rl > div {
  display: inline-block;
  border: solid;
  margin: 0 5px;
}
</style>
<p>Test passes if the blue, orange, brown boxes are identical.

<div class=v-rl>
  <div id=test>あいう<span></span>えお<span></span></div>
  <br>
  <div id=test2>あいう<span></span>えお<span></span></div>
  <br>
  <div id=ref>あいう<span></span>えお<span></span></div>
</div>