Tab效果如何去掉上面块和下面块之间的border呢
<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<style type="text/css">
body { margin:0; padding:0; }
ul.tab { margin:0 auto; width:150px; }
ul,li { margin:0; padding:0; }
ul { list-style:none; }
ul li { float:left; position:relative; line-height:30px; }
ul li a { display:block; padding:0 10px; text-decoration:none; width:50px; }
ul li ul { position:absolute; right:-1px; top:30px; display:none; }
ul li a:link,ul li a:visited { color:#FFF; background:#F00; }
ul li a:hover,ul li a:active { color:#000; background:#CCC; }
ul li ul li a { width:100px; }
</style>
<script type="text/javascript">
function showMune(obj) {
obj.getElementsByTagName("ul")[0].style.display = "block";
obj.getElementsByTagName("ul")[0].style.border = "1px solid #000";
obj.style.border = "1px solid #000";
obj.style.borderBottom = "1px solid #ccc";
}
function hideMune(obj) {
obj.getElementsByTagName("ul")[0].style.display = "none";
obj.getElementsByTagName("ul")[0].style.border = "none";
obj.style.border = "none";
obj.style.borderBottom = "none";
}
</script>
</head>
<body>
<ul class="tab">
<li onmouseover="showMune(this)" onmouseout="hideMune(this)">
<a href="#">中国</a>
<ul>
<li><a href="#">中国</a></li>
<li><a href="#">中国</a></li>
<li><a href="#">中国</a></li>
<li><a href="#">中国</a></li>
</ul>
</li>
<li onmouseover="showMune(this)" onmouseout="hideMune(this)">
<a href="#">中国</a>
<ul>
<li><a href="#">中国</a></li>
<li><a href="#">中国</a></li>
<li><a href="#">中国</a></li>
<li><a href="#">中国</a></li>
</ul>
</li>
</ul>
</body>
</html>
代码如上,如何去掉上面块和下面块之间的border呢
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