请问为什么红框区没有老师的切换样式？谢谢！
<!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=gb2312" />
<title>我的Web前端开发自学生涯</title>
<link href="mine.css" rel="stylesheet" type="text/css"/>
<script src="js/setHomeSetFav.js" type="text/javascript"></script>
<script src="js/myfocus-2.0.1.min.js" type="text/javascript"></script>
<script src="js/mf-pattern/mF_fancy.js" type="text/javascript"></script>
<link href="js/mf-pattern/mF_fancy.css" type="text/css"/>
<script type="text/javascript">
myFocus.set({
id:'picBox'});
</script>
</head>
<body>
<div class="top">
<div class="top_content">
<ul>
<li><a href="#" onclick="SetHome(window.location)">设为首页</a></li>
<li><a href="#" onclick="AddFavorite(window.location,document.title)">加入收藏</a></li>
<li><a href="#">联系我们</a></li>
</ul>
</div>
</div><!--top结束-->
<div class="wrap">
<div class="logo">
<div class="logo_left">
<img src="images/logo.jpg" alt="慕课网"/>
</div>
<div class="logo_right">
<img src="images/tel.jpg" alt="服务热线"/>24小时服务热线: <span class="tel">123-456-7890</span>
</div>
</div><!--logo结束-->
<div class="nav">
<div class="nav_left"></div>
<div class="nav_mid">
<div class="nav_mid_left">
<ul>
<li><a href="#">首页</a></li>
<li><a href="list.html">关于慕课</a></li>
<li><a href="list.html">新闻动态</a></li>
<li><a href="list.html">课程中心</a></li>
<li><a href="list.html">在线课程</a></li>
<li><a href="list.html">人才招聘</a></li>
</ul>
</div>
<div class="nav_mid_right">
<form action="" method="post">
<input type="text" class="search_text"/>
</form>
</div>
</div><!--nav_mid结束-->
<div class="nav_right"></div>
</div><!--nav结束-->
<div class="ad" id="picBox">
<div class="pic">
<ul>
<li><img src="images/ad2.jpg" /></li>
<li><img src="images/ad3.jpg" /></li>
<li><img src="images/ad4.jpg" /></li>
</ul>
</div>
</div><!--ad结束-->
</div><!--wrap结束-->
</body>
</html>
