<head>
<style type="text/css">
.aa div p{ width:200px; height:200px; background:blue; }
.bb{ width:100px; height:100px; background:red; }
</style></head><body>
<div class="aa">
<div>
<p class="bb"></p>
</div>
<div>
<p></p>
</div>
</div></body>
