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 PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" 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{ 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;34%;height:26px;margin-left:-1px;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{33%;box-shadow:none;margin-left:0px;}
.news_info a:last-child{33%;border-right:none;margin-left:-1px;}
.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);}
.news_info a:hover:first-child, .news_info a.current:first-child{border-top-left-radius:4px;border-bottom-left-radius:4px;}
.news_info a:hover:last-child, .news_info a.current:last-child{border-top-right-radius:4px;border-bottom-right-radius:4px;}
</style>
</head>
<body>
<div class="jikey_demo">
<nav class="news_info"><a class="current" href="/news/">新闻1</a><a class="" href="/guide/">新闻2</a><a class="" href="/review/">新闻3</a></nav>
</div>
</body>
</html>