子div 相对于 父div 底部对齐

<style type="text/css">
.box1 {border:1px #cccccc solid;  width:500px; height:600px;position:relative;}
.box2 {border-top:1px #cccccc solid; background:#f2f6fb; width:498px; height:22px; position:absolute; bottom:0;}
 </style>

 <div class="box1">  
  <div class="box2">
</div>
</div>