chromium/third_party/blink/web_tests/external/wpt/css/css-conditional/container-queries/pseudo-elements-002.html

<!DOCTYPE html>
<title>CSS Container Queries Test: Container for ::before/::after pseudo elements</title>
<link rel="help" href="https://drafts.csswg.org/css-conditional-5/#container-queries">
<link rel="match" href="pseudo-elements-002-ref.html">
<style>
  .container { container-type: inline-size; }

  @container (max-width: 100px) { #c1::before { content: "PASS" } }
  @container (min-width: 150px) { #c1::before { content: "FAIL" } }

  @container (max-width: 100px) { #c2::before { content: "PASS" } }
  @container (min-width: 150px) { #c2::before { content: "FAIL" } }

  @container (max-width: 100px) { #c3::after { content: "PASS" } }
  @container (min-width: 150px) { #c3::after { content: "FAIL" } }

  @container (max-width: 100px) { #c4::after { content: "PASS" } }
  @container (min-width: 150px) { #c4::after { content: "FAIL" } }
</style>
<div id="c1" class="container" style="width:100px"></div>
<div id="c2" class="container" style="width:200px"></div>
<div id="c3" class="container" style="width:100px"></div>
<div id="c4" class="container" style="width:200px"></div>
<script>
  document.body.offsetTop;
  c2.style.width = "100px";
  c4.style.width = "100px";
</script>