<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
* {
margin: 0px;
padding: 0px;
}
#daohanglan {
height: 35px;
/*border: 1px solid black;*/
width: 280px;
position: relative;
/*top: 0px;*/
z-index: 200;
}
.annv {
float: left;
width: 70px;
max-height: 35px;
background-color: darkcyan;
text-align: center;
line-height: 35px;
overflow: hidden;
}
ul {
list-style: none;
}
.annv:hover{
max-height: 300px;
transition: 1s;
}
li{
background-color: darkmagenta;
}
</style>
</head>
<body>
<div id="daohanglan">
<div class="annv">首页</div>
<div class="annv">PHP
<ul>
<li>1111</li>
<li>222222</li>
<li>444</li>
</ul>
</div>
<div class="annv">JAVA
<ul>
<li>1111</li>
<li>222222</li>
<li>333</li>
<li>444</li>
</ul>
</div>
<div class="annv">.NET
<ul>
<li>1111</li>
<li>222222</li>
</ul>
</div>
</div>
<div style="position: absolute;z-index: 100;">
啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦
啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦啦
</div>
</body>
</html>
原文：http://www.cnblogs.com/skyhorseyk/p/6979109.html