chromium/third_party/blink/web_tests/printing/monolithic-at-page-block-end-vertical-rl.html

<!DOCTYPE html>
<script>
  if (window.testRunner)
      testRunner.setPrinting();
  if (window.internals)
      internals.settings.setShouldPrintBackgrounds(true);
</script>
<style>
  html { writing-mode: vertical-rl; }
  body { margin: 0; }
</style>
<div style="contain:size; position:absolute; left:0; width:100px; height:100px;">
  <div style="margin-left:-100px; width:200px; height:100px; background:blue;"></div>
</div>
<p style="writing-mode:horizontal-tb; margin-left:1em; margin-top:150px;">
  When printed, there should be two pages. There should be a blue square on
  each page. On the first page, the square should be at the left-hand side of
  the page, and on the second page, it should be at the right-hand side.
</p>
<div style="break-before:page; block-size:10px;"></div>