address:empty { background: lime; }
 address { background: red; margin: 0; height: 1em; }
 .text { margin: -1em 0 0 0; }

 <address><!-- --><?test random PI></address>
 <div class="text">This line should have a green background.</div>

 <p>(Note. This test is based on an <a href="http://lists.w3.org/Archives/Member/w3c-css-wg/2001OctDec/thread.html#140">controversial and unpublished clarification to the spec</a> and is included for completeness only. Without the clarification, the spec says this test should be red, not green.)</p>