[JavaScript] css places the footer at the bottom of the page

<!-- 父层 -->  
<div id="wapper">  
    <!-- 主要内容 -->  
    <div id="main-content">  
    </div>  
    <!-- 页脚 -->  
    <div id="footer">  
    </div>  
</div>  

#wapper {   
    position : relative ;    /* Important! Ensure that the footer is absolute relative to the wapper position */   
    height : auto ;           /* Ensure that the page can be displayed normally when the browser height is stretched */   
    min-height : 100%   /* IE6 does not support, IE6 needs to be configured separately */   
}   
#footer {   
   position : absolute ;   bottom : 0 ; /* Key */   
   left : 0 ; /* Be sure to remember under IE */   
   height :60px ;          /* The height of the footer must be a fixed value */   
}   
#main-content {   
   padding-bottom : 60px ; /* Important! Space reserved for footer */   
}  

<!--[if IE 6]->  
<style>  
#wapper { height : 100% ;} /* IE will automatically spread the layer when the height is not enough */  
</style>  
<![endif]-->