style_element_with_dynamic_css.html

<html>
<head>
<meta charset="utf8">
<title>Test style element with dynamically updated CSS</title>
<style id="style1" type="text/css"></style>
<style id="style2" type="text/css">h1: {color: green;}</style>
<script>
function Run() {
  document.getElementById("style1").sheet.insertRule("div { color: blue; }", 0);
  document.getElementById("style2").sheet.insertRule("p { color: red; }", 0);
}
</script>
</head>
<body onload="Run()">
  <h1>Title</h1>
  <div>Hello</div>
  <p>World</p>
</body>
</html>

chromium/third_party/blink/renderer/core/testing/data/frameserialization/style_element_with_dynamic_css.html