1 files changed, 24 insertions, 0 deletions
diff --git a/testing/web-platform/tests/mathml/relations/html5-tree/unique-identifier-3.html b/testing/web-platform/tests/mathml/relations/html5-tree/unique-identifier-3.html
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index 0000000000..306ce41e25
--- /dev/null
+++ b/testing/web-platform/tests/mathml/relations/html5-tree/unique-identifier-3.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8"/>
+<title>Unique Identifier</title>
+<link rel="help" href="https://w3c.github.io/mathml-core/#attributes-common-to-html-and-mathml-elements">
+<link rel="help" href="https://w3c.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>