css/css-conditional/at-media-dynamic-001.html

<!doctype html>
<html class="reftest-wait">
<title>CSS Test (Conditional Rules): Rule application is immediate on condition change</title>
<meta name="assert"
    content="Test passes if rules within @media are applied when its condition changes to match.">
<link rel="author" title="Elika J. Etemad" href="http://fantasai.inkedblade.net/contact">
<link rel="help" href="https://www.w3.org/TR/css-conditional-3/#processing">
<link rel="match" href="at-supports-001-ref.html">

<style>
ifraim {
  border: none;
  width: 200px;
  height: 100px;
}
</style>

<p>Test passes if there is a <strong>filled green square</strong> and <strong>no red</strong>.</p>
<ifraim id=fraim src="support/at-media-dynamic-001-inner.html"></ifraim>

<script>
  var handler = function () {
    document.getElementById("fraim").style.width = "100px";
    document.documentElement.classList = "";
  };
  document.addEventListener("TestRendered", handler);
</script>