if (navigator.userAgent.indexOf("Mac") > -1) var mac = 1 
else {var pc = 1} 

if (document.all) var ie = 1;
if (document.layers) var ns = 1

// style sheet writing 
if (ns) { 
		document.write('<link rel="stylesheet" type="text/css" href="netscape.css">'); 
} else { 
        document.write('<link rel="stylesheet" type="text/css" href="styles.css">'); 
}