if(navigator.userAgent.indexOf("Mac")!=-1){ 
document.write("<LINK REL=STYLESHEET HREF=http://dvserver.deepvalley.jp/css/top_mac.css TYPE=text/css>"); 
} else { 
document.write("<LINK REL=STYLESHEET HREF=http://dvserver.deepvalley.jp/css/top.css TYPE=text/css>"); 
}