<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<title>Unique Identifier</title>
<link rel="help" href="https://mathml-refresh.github.io/mathml-core/#attributes-common-to-html-and-mathml-elements">
<link rel="help" href="https://mathml-refresh.github.io/mathml-core/#css-styling">
<link rel="match" href="unique-identifier-3-ref.html"/>
<meta name="assert" content="Verify that the id attribute affects CSS selectors.">
<style>
  #fail { display: none; }
  #pass { background: green; }
</style>
</head>
<body>

  <p>Test passes if you see the text "PASS".</p>
  <math>
    <mtext id="fail" style="background: red; color: white;">FAIL</mtext>
    <mtext id="pass" style="color: white;">PASS</mtext>
  </math>

</body>
</html>