<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
<html lang="en">
 <head>
  <title>Margin Collapsing: negative margins (easy)</title>
  <style type="text/css">
   .ahem { display: inline; font: 1em/1 Ahem, sans-serif; background: red; color: white; }
   .test { border: solid; background: red; width: 5em; font: 1em/1em Ahem; }
   .test .a { height: 0; margin: 0 0 1em 0; background: red; color: lime; }
   .test .b { height: 1em; margin: 1em 0 0 0; background: lime; }
  </style>
 </head>
 <body>
  <div class="ahem">Ahem_font_required_for_this_test.</div>
  <p>There should be no red below.</p>

  <div class="test">
   <p class="a">XXXXX</p>
   <p class="b"></p>
  </div>

 </body>
</html>