<!DOCTYPE html>
<html>
  <head>
    <title>CSS Reftest Reference</title>
    <link rel="author" title="Aryeh Gregor" href="mailto:ayg@aryeh.name">
    <style>
      span::before {
        display: block;
        content: 'abc';
      }
    </style>
  </head>
  <body>
    <span>def</span>
  </body>
</html>