if ((navigator.userAgent.indexOf("Mac") != -1))  
	document.write("<link rel='stylesheet' href='http://www.nct.co.jp/css/mac.css'>")  
if (navigator.userAgent.indexOf('Win') != -1){  
	if (navigator.appName.indexOf('Netscape') != -1) { 
		document.write("<link rel='stylesheet' href='http://www.nct.co.jp/css/pc_nc.css'>") 
		} 
		else {  
			document.write("<link rel='stylesheet' href='http://www.nct.co.jp/css/pc_ie.css'>") 
		} 
	}