<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>测试</title>
<style>
*{
margin:0px;
padding:0px;
}
.page {
width:100%;
height:100%;
}
.nav {
width:160px;
height:205px;
position: fixed;
left: 0;
top: 50%;
margin-top: -103px;
}
.nav-li {
width: 160px;
height: auto;
color: #FFF;
line-height: 40px;
background: #333;
text-align: center;
font-size: 16px;
border-bottom:1px solid #FFF;
cursor: pointer;
}
.tit {
width: 160px;
height: 40px;
}
.nav-li:hover ul {
display: block;
}
.nav-li ul {
width: 160px;
height: auto;
background: #FFFFFF;
display: none;
}
.nav-li ul li {
width: 160px;
height: 40px;
border-bottom:1px dashed #666;
color: #333;
text-align: center;
line-height: 40px;
position: relative;
}
.nav-li ul li:hover .list-3 {
display: block;
}
.list-3 {
width: 160px;
height: auto;
position: absolute;
left: 160px;
top: 0px;
display: none;
}
.list-3Dom {
width: 160px;
height: 40px;
background: #444;
border-bottom:1px dashed #666;
color: #FFF;
text-align: center;
line-height: 40px;
}
</style>
</head>
<body>
<div class="page">
<div class="nav">
<div class="nav-li">
<div class="tit">慕课网的标题(一)</div>
<ul>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
</ul>
</div>
<div class="nav-li">
<div class="tit">慕课网的标题(二)</div>
<ul>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
</ul>
</div>
<div class="nav-li">
<div class="tit">慕课网的标题(三)</div>
<ul>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
<li>
二级栏目
<div class="list-3">
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
<div class="list-3Dom">三级栏目</div>
</div>
</li>
</ul>
</div>
<div class="nav-li">
</div>
</div>
</body>
</html>效果图：
笔记
鼠标指向导航栏1级出现2级时：
1级:hover 2级{
display:block;
}
2级{
display:none;
}