为什么只显示em背景只显示蓝色
<style type="text/css">
/*在此定义相关CSS样式*/
ul li{padding:0;margin:0;font-size:12px;}
.topList{
width:300px;
height:180px;
border:1px solid #E8E8E8;
margin:0 auto;
}
.topList ul {
padding: 0 2px;
height:28px;
}
.topList li{
padding-right:2px;
list-style-type:none;
}
.top em{
background-color:blue;
display:block;
width:20px;
height:16px;
color:white;
background: url( http://img1.sycdn.imooc.com//53cf0fa20001d3dc00200032.jpg)no-repeat ;
background-position:0 0;
line-height:16px;
}
em{
font-style:normal;
font-size:12px;
float:left;
display:block;
width:20px;
height:16px;
text-align:center;
color:#333;
background-position:-16px 0 ;
background: url( http://img1.sycdn.imooc.com//53cf0fa20001d3dc00200032.jpg)no-repeat ;
line-height:16px;
}
a{
font-size:12px;
font-family:"微软雅黑";
}
a:link,a:visited{
text-decoration:none;
color:gray;
}
a:hover,a :active{
text-decoration:none;
color:red;
}
</style>
){kind=link}