ad>
 <body>
  <p>Test passes if there is a short green rectangle and <strong>no red</strong>.</p>
  <div class="container"><div class="test">ppp</div></div>

  <!-- "p" is like an underscore in Ahem. -->

  <!-- the result will be that if the line-height is 0, then the
       container will be visible as the test will be height:0 and the
       text will overflow the test with a small green line, leaving
       the red of the container visible. otherwise, line-height is
       1, the test block will grow to