<!DOCTYPE html>
CSS4-布局2-display下拉菜单案例
<style>
.xiala{width:200px;background:#ddd;}
.xiala li div{position:absolute;width:150px;height:150px;background:#999;}
/*下拉菜单代码*/
.xiala li div{display:none;}
.xiala li:hover div{display:block;}
</style>
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<ul class="xiala">
<li>
<a href="###">下拉菜单</a>
<div>下拉菜单内容</div>
</li>
</ul>
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原文：http://www.cnblogs.com/lyp123/p/5662927.html