function mm_changeStyle(file){
　　 document.getElementById("cssStyle").setAttribute("href",file); 
     setCookie('css_file',file,  '720')
} 

function getCookie(name){
if (document.cookie.length>0){ 
c_start=document.cookie.indexOf(name + "=")
if (c_start!=-1){ 
c_start=c_start + name.length+1 
c_end=document.cookie.indexOf(";",c_start)
if (c_end==-1) c_end=document.cookie.length
return unescape(document.cookie.substring(c_start,c_end))
} 
}
return null
}

function setCookie(name,value,  hours)  
{  
   var  expire  =  "";  
   if(hours  !=  null)  
   {  
       expire  =  new  Date((new  Date()).getTime()  +  hours  *  3600);  
       expire  =  ";  expires="  +  expire.toGMTString();  
   }  
   document.cookie  =  name  +  "="  +  escape(value)  +  expire;  
}