主要运用的dispaly将a变成行内块，再用padding撑开宽度。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
.nav {
height: 40px;
background: #eee;
border-top: 3px solid orange;
border-bottom: 1px solid #aaa;
}
.nav-con {
1000px;
height: 40px;
margin: 0 auto;
}
a {
font: 12px/40px 微软雅黑; /*40px=>line-height:40px;*/
color: #333;
display: inline-block;
height: 40px;
text-decoration: none;
padding: 0 12px;
}
a:hover {
background: #999;
}
</style>
</head>
<body>
<div class="nav">
<div class="nav-con">
<a href="#">设为首页</a>
<a href="#">手机新浪网</a>
<a href="#">移动客户端</a>
</div>
</div>
</body>
</html>