作业：导航条的制作
<!doctype html>
<html>
<head>
<title>导航</title>
<style type="text/css">
*{margin: 0px;padding: 0px;}
a{text-decoration: :none;color: #BDBEBE;font-size: 13px;}
.clear{clear: both;}
.header{width: 100%;height: 40px;background-color: #E3E4E5;}
.header_content{width: 1200px;height: 40px;margin: 0px auto;}
.header_left{height: 40px;line-height: 40px;float: left;}
.header_a:hover{color: #FF5000;background-color: white;}
.header_right{width: 800px;height: 40px;line-height: 40px;float: right;}
.header_a{display: inline-block;height: 40px;line-height: 40px; text-align: center;}
</style>
</head>
<body>
<div class="header">
<div class="header_content">
<div class="header_left">
<a class="header_a">北京<i class=" fa fa-angle-down"></i></a><span> </span>
</div>
<div class="header_right">
<a href="#">你好，请登录</a>
<span> </span>
<a href="" style="color:red">免费注册</a>
<span> |</span>
<a href="">我的订单</a>
<span> |</span>
<a href="" class="header_a">我的京东</a>
<span> |</span>
<a href="">京东会员</a>
<span> |</span>
<a href="" class="header_a">企业采购</a>
<span> |</span>
<a href="" class="header_a">客户服务</a>
<span> |</span>
<a href="" class="header_a">网站导航</a>
<span> |</span>
<a href="">手机京东</a>
</div>
</div>
<div class="clear"></div>
</div>
</body>
</html>命令使用不熟悉，需要翻看之前的笔记才能完成。练习量不够。
