css/css-contain/contain-html-t-o-003.html

<!doctype html>
<html lang=en>
  <meta charset=utf-8>
  <title>CSS-contain test: size containment on html prevents text-orientation propagation</title>
  <link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net">
  <meta name=flags content="">
  <meta name=assert content="size containment on html prevents text-orientation propagation">
  <link rel="match" href="reference/contain-body-t-o-001-ref.html">
  <link rel=help href="https://drafts.csswg.org/css-contain-1/#contain-property">

<style>
html {
    writing-mode: vertical-lr;
    direction: rtl;
    width: 100vw;
    height: 100vh;
    overflow: hidden;
}
body {
    margin: 0;
    border-top: 100px solid red;
    border-bottom: 100px solid green;
    width: 100vw;
    height: 100vh;
    text-orientation: upright;
}
html {
    contain: size;
}
p {
    margin: auto;
    padding: 150px 0;
    writing-mode: horizontal-tb;
    direction: ltr;
}
</style>

<p>Test passes if there is no red.