实现的难点在于：first-child,last-child 两个选择器，以后margin-left:-1px;的应用，33%,34%宽度的技巧处理。
另外一个难点是：box-shadow:1px 0 0 #F1F1F1 inset; 的实现。
最后是：
background:-webkit-gradient(linear, left top, left bottom, from(#f9f9f9), to(#b6b4b4));background:-moz-linear-gradient(top, #f9f9f9, #b6b4b4);background:-o-linear-gradient(top, #f9f9f9, #b6b4b4);background:linear-gradient(top, #f9f9f9, #b6b4b4);
<!doctype html>
<html xmlns="<a href="http://www.w3.org/1999/xhtml">http://www.w3.org/1999/xhtml</a>" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8"/>
<title>html5,css3菜单</title>
<style type="text/css">
.jikey_demo{ width:80%; margin:0 auto; background:#f1f1f1;}
.news_info{margin-bottom:5px;border:1px solid #bbb;border-radius:5px;box-shadow:0 1px 0 #f1f1f1;}
.news_info a{display:inline-block;width:33%;height:26px;font-family:"微软雅黑";line-height:26px;text-align:center;color:#555;border-right:1px solid #ccc;box-shadow:1px 0 0 #F1F1F1 inset;}
.news_info a:first-child{width:33%;box-shadow:none;border-radius:4px 0 0 4px;}
.news_info a:last-child{width:34%;border-right:none;margin-left:-2px;border-radius:0 4px 4px 0;}
.news_info a:hover, .news_info a.current{color:#208edd;background:-webkit-gradient(linear, left top, left bottom, from(#f9f9f9), to(#b6b4b4));background:-moz-linear-gradient(top, #f9f9f9, #b6b4b4);background:-o-linear-gradient(top, #f9f9f9, #b6b4b4);background:linear-gradient(top, #f9f9f9, #b6b4b4);}
</style>
</head>
<body>
<div>
<nav><a href="/news/">新闻1</a><a href="/guide/">新闻2</a><a href="/review/">新闻3</a></nav>
</div>
</body>
</html>