图片和span水平垂直居中

<style type="text/css">  
.content{  
    width:20%;  
    height:60px;  
    border:1px solid red;  
    text-align:center;
}  
span{  
    height:100%;  
    vertical-align:middle;  
    line-height:60px;
}  
img{  
    vertical-align:middle;
}  
</style>  
<div class="content">  
    <img src="1.jpg">  
    <span>测试一下吧</span>  
</div>