abstract:<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title> New Document </title> <style type="text/css"> 
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title> New Document </title>
<style type="text/css">
*{ margin:0px; padding:0px;}
#nav{ width:600px; height:40px; margin:0 auto;}
#nav ul{ list-style:none;}
#nav ul li{ float:left; line-height:40px; text-align:center; position:relative;}
#nav ul li a{ text-decoration:none; color:#000; display:block;padding:0px 10px;}
#nav ul li a:hover{ color:#FFF; background:#333}
#nav ul li ul{ position:absolute; display:none;}
#nav ul li ul li{ float:none; line-height:30px; text-align:left;}
#nav ul li ul li a{ width:100%;}
#nav ul li ul li a:hover{ background-color:#06f;}
#nav ul li:hover ul{ display:block}
</style>
</head>
<body>
<div id="nav">
<ul>
<li><a href="#">首页</a></li>
<li><a href="#">学习中心</a>
<ul>
<li><a href="#">java</a></li>
<li><a href="#">jQuery</a></li>
<li><a href="#">C++</a></li>
<li><a href="#">C语言</a></li>
</ul>
</li>
<li><a href="#">个人中心</a></li>
<li><a href="#">关于我们</a></li>
</ul>
</div>
</body>
</html>
Correcting teacher:天蓬老师Correction time:2019-03-20 17:31:34
Teacher's summary:css中的hove, javascript中的鼠标悬停事件, 有很多相似的地方, 有空了解一下