简单的实现下拉菜单（样式）
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>下拉菜单</title>
<style type="text/css">
.container{
width: 1000px;
margin: 0px auto;
}
.nav>ul{
list-style: none;
}
.nav>ul>li{
display: inline-block;
margin-right: 20px;
}
.nav>ul a{
text-decoration: none;
}
.submenu{
list-style: none;
padding: 0px;
display: none;
position: absolute;
}
.nav>ul>li:hover .submenu{
display: block;
}
</style>
</head>
<body>
<div class="container">
<div class="nav">
<ul>
<li><a href="#">首页</a></li>
<li><a href="#">产品中心</a></li>
<li>
<a href="#">新闻中心</a>
<ul class="submenu">
<li><a href="#">国内新闻</a></li>
<li><a href="#">国际新闻</a></li>
</ul>
</li>
<li><a href="#">关于我们</a></li>
<li><a href="#">联系我们</a></li>
</ul>
</div>
</div>
</body>
</html>
