li无法显示在同一行!明明有位置
<!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>3.10新闻中心制作评测题</title>
<style type="text/css">
*{margin:0;padding:0;}
.topList{width:300px;height:180px;border:1 solid #E8E8E8;margin:0 auto;}
.topList li{display:block;float:left;list-style-type:none;line-height:16px;text-decoration:none;font-family:"微软雅黑";}
.topList em{float:left;width:20px;height:16px;text-align;font-style:normal;color:#333;background:url(http://img1.sycdn.imooc.com//53cf0fa20001d3dc00200032.jpg) no-repeat;background-position:bottom;line-height:16px;}
.top em{background-position:top;}
a{text-decoration:none;color:grey;}
a:hover,a:active{color:red;}
ul{padding:5px;}
</style>
</head>
<body>
<div class="topList">
<ul>
<li class="top"><em>01</em>
<p><a href="http://www.imooc.com/" >【慕客访谈用户篇】“有为屌丝”在路上</a></p>
</li>
<li class="top"><em>02</em>
<p><a href="http://www.imooc.com/">【有奖活动】给父亲的三行书信</a></p>
</li>
<li class="top"><em>03</em>
<p><a href="http://www.imooc.com/">《程序猿,请晒出你的童年》活动获奖公告</a></p>
</li>
<li><em>04</em>
<p><a href="http://www.imooc.com/">【慕课访谈】破茧成蝶——美女程序员的蜕变史</a></p>
</li>
<li><em>05</em>
<p><a href="http://www.imooc.com/">【获奖公告】追“球”巅峰,争当“预言帝”</a></p>
</li>
<li><em>06</em>
<p><a href="http://www.imooc.com/">【问卷调查】慕课网用户学习情况大调查</a></p>
</li>
</ul>
</div>
</body>