css/css-pseudo/highlight-styling-004.html

<!doctype html>
<meta charset="utf-8">
<title>CSS Pseudo-Elements Test: the light-dark() function in highlight pseudos</title>
<link rel="author" title="Stephen Chenney" href="mailto:schenney@chromium.org">
<link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#highlight-styling">
<link rel="match" href="highlight-styling-004-ref.html">
<meta name="assert" value="This test verifies that ::selection styles make use of the light-dark() function.">
<script src="support/selections.js"></script>
<link rel="stylesheet" href="support/highlights.css">
<style>
  :root {
    color-scheme: light dark;
  }

  .light {
    color-scheme: light;
  }

  .dark {
    color-scheme: dark;
  }

  p::selection {
    color: light-dark(green, blue);
  }
</style>
<p>Test passes if Light is green and Dark is blue.</p>
<main class="highlight_reftest">
    <p class="light">Light</p>
    <p class="dark">Dark</p>
</main>
<script>selectNodeContents(document.querySelector("main"));</script>