<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>三级菜单</title>
<style>
a {
color: #FFFF99;
text-decoration: none;
}
a:hover {
color: #FFFFFF;
text-decoration: underline;
}
.top-nav {
font-size: 16px;
font-weight: bold;
list-style: none;
overflow: auto;
}
.top-nav li {
float: left;
}
/* 二级菜单 */
.top-nav li ul {
display: none;
/* 去圆点 */
list-style: none;
padding: 0px;
position: relative;
}
.top-nav li a:hover {
background-color: red;
}
.top-nav li:hover ul {
display: block;
/* 为了竖向显示 定义一个宽度 */
width: 80px;
}
/* 三级菜单 */
.top-nav li:hover ul li ul {
display: none;
}
/* 鼠标移动到二级菜单时 三级菜单显示 */
.top-nav li ul li:hover ul {
display: block;
top: 0px;
left: 80px;
position: absolute;
}
.top-nav li a {
line-height: 20px;
text-decoration: none;
background: #DDDDDD;
color: #666666;
display: block;
width: 80px;
text-align: center;
}
</style>
</head>
<body>
<div id="top">
<ul class="top-nav">
<li><a href="#">首页</a></li>
<li><a href="#">课程大厅</a></li>
<li><a href="#">学习中心</a>
<ul>
<li><a href="#">前端课程</a>
<ul>
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</ul>
</li>
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<li><a href="#">移动开发</a></li>
</ul>
</li>
<li><a href="#">经典案例</a></li>
<li><a href="#">关于我们</a></li>
</ul>
</div>
</body>
</html>
