二级导航为嘛显示不了？
无法二级导航无法覆盖到之上
<!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" />
<meta name="keywords" content="WOW Hotel" />
<meta name="description" content="WOW Hotel" />
<link rel="stylesheet" type="text/css" href="css/style.css" />
<title>WOW Hotel -- Home</title>
<script type="text/javascript">
function showmenu(elmnt)
{
document.getElementById(elmnt).style.display = "block";
}
function hidemenu(elmnt)
{
document.getElementById(elmnt).style.display = "none";
}
</script>
</head>
<body>
<!--顶端样式-->
<div id="top">
<!--头部样式-->
<div id="header">
<div id="logo"><img src="images/BfAVS0Lk.png" width="292" height="102"/></div>
<div id="logon_text"></div>
</div>
<!--导航样式-->
<div id="nav">
<div id="nav_bg">
<div class="nav_top">
<ul>
<li><a href="index.html">Home</a></li>
<li onmouseover="showmenu('tutorials2')" onmouseout="hidemenu('tutorials2')"><a href="#">Packages</a>
<ul class="menu" id="tutorials2" style="display:none;">
<li class="menu"><a href="#">1</a></li>
<li class="menu"><a href="#">2</a></li>
<li class="menu"><a href="#">3</a></li>
<li class="menu"><a href="#">4</a></li>
</ul>
</li>
<li onmouseover="showmenu('menus2')" onmouseout="hidemenu('menus2')"><a href="#">Rooms</a>
<ul class="menu" id="menus2" style="display:none;">
<li class="menu"><a href="#">1</a></li>
<li class="menu"><a href="#">2</a></li>
<li class="menu"><a href="#">3</a></li>
<li class="menu"><a href="#">4</a></li>
</ul>
</li>
<li onmouseover="showmenu('menus3')" onmouseout="hidemenu('menus3')"><a href="#">Entertainment</a>
<ul class="menu" id="menus3" style="display:none;">
<li class="menu"><a href="#">1</a></li>
<li class="menu"><a href="#">2</a></li>
<li class="menu"><a href="#">3</a></li>
<li class="menu"><a href="#">4</a></li>
</ul>
</li>
<li onmouseover="showmenu('menus4')" onmouseout="hidemenu('menus4')"><a href="#">Server</a>
<ul class="menu" id="menus4" style="display:none;">
<li class="menu"><a href="#">1</a></li>
<li class="menu"><a href="#">2</a></li>
<li class="menu"><a href="#">3</a></li>
<li class="menu"><a href="#">4</a></li>
</ul>
</li>
<li onmouseover="showmenu('menus5')" onmouseout="hidemenu('menus5')"><a href="#">BBS</a>
<ul class="menu" id="menus5" style="display:none;">
<li class="menu"><a href="#">1</a></li>
<li class="menu"><a href="#">2</a></li>
<li class="menu"><a href="#">3</a></li>
<li class="menu"><a href="#">4</a></li>
</ul>
</li>
<li onmouseover="showmenu('menus6')" onmouseout="hidemenu('menus6')"><a href="#">Contact</a>
<ul class="menu" id="menus6" style="display:none;">
<li class="menu"><a href="#">1</a></li>
<li class="menu"><a href="#">2</a></li>
<li class="menu"><a href="#">3</a></li>
<li class="menu"><a href="#">4</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="banner">
<img src="images/banner.jpg" />
</div>
</div>
</div>
<!--main-->
<div id="main">
<div id="i_left">
<div>
<h3 class="blk_t">Navigation</h3>
<ul>
<li><a href="sp.html">Spend a weekend</a></li>
<li><a href="sp.html">Anywhere sale</a></li>
<li><a href="sp.html">Breakfast package</a></li>
<li><a href="sp.html">Romance package</a></li>
</ul>
</div>
</div>
<div id="center"></div>
<div id="i_right"></div>
</div>
<!--footer-->
<div id="footer"></div>
</body>
</html>
/*-----------------------------------// 全局样式 //-----------------------------------*/
body{ margin:0px; padding:0px; background-image:url(../images/top_bg.jpg); background-repeat: repeat-x; font:12px/180% Arial,"宋体",Helvetica, sans-serif,Verdana;}
/*--- top ---*/
#top{ width:100%; height:471px; margin:0px auto; }
/*-----------------------------------// 头部样式 //-----------------------------------*/
#header{ width:940px; height:100px; margin:0px auto; overflow: hidden; }
#logo{ float:left;}
#logon_text{}
/*-----------------------------------// 导航样式 //-----------------------------------*/
#nav{ margin:0px auto; }
#nav_bg{ margin:0px auto; width:940px; height:42px; background:url(../images/nav_right.gif) no-repeat;}
.nav_top ul{ margin:0px; padding:0px; list-style-type:none; }
.nav_top ul li{ float:left;line-height: 42px; width:120px; text-decoration:none; text-align:center;}
.nav_top li a,.nav_top li a:visited{display: block; text-decoration: none;color:#fff; font-weight: bold; font-size:13px;}
.nav_top ul li a:hover{background:url(../images/menu_hover.gif) no-repeat;}
.menu {background:url(../images/menu_hover.gif) no-repeat; position:absolute;}
.menu li{list-style:none; }
#banner{ clear:both;margin:0px auto; margin-top:4px; width:940px;}
/*--- 主体页面 ---*/
#main{ width:980px; height:481px; margin:0px auto; margin-top:3px; border:1px solid #070707;}
/*-----------------------------------// 首页 //-----------------------------------*/
/*----// 左侧 //----*/
#i_left{ float:left; width:210px;}
/*----// 居中 //----*/
#center{ float:left; width:498px;}
/*----// 右侧 //----*/
#i_right{float:left; width:210px;}
/*footer*/
#footer{ width:940px; height:49px; margin:0px auto; border:1px solid #070707;}
