315620-2-ref.xhtml

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<html xmlns="http://www.w3.org/1999/xhtml">

<head>

  <style>

    <![CDATA[

      div { background: red; height: 3em; }

      div:empty { background: lime; }

]]>

  </style>

</head>

<body>

  <div></div>

</body>

</html>