<!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 {
  -webkit-text-combine: horizontal; /*testing the layout text-combine, not it's support in general*/
  text-combine-upright: all;
  white-space: normal;
}
#test { color: blue; }
#ref { color: orange; }
</style>
<p>Test passes if the blue and orange lines of text are identical.

<div class=v-rl>
  <div id=test>あ<span>12</span>い<span>34</span>う<span>5&nbsp;6</span>えお</div>
  <div id=ref>あ<span>12</span>い<span>34</span>う<span>5&nbsp;6</span>えお</div>
</div>