// convert all characters to lowercase to simplify testing
    var agt=navigator.userAgent.toLowerCase();

    // *** BROWSER VERSION ***
    // Note: On IE5, these return 4, so use is_ie5up to detect IE5.
    var is_major = parseInt(navigator.appVersion);
    var is_minor = parseFloat(navigator.appVersion);

    // Note: Opera and WebTV spoof Navigator.  We do strict client detection.
    // If you want to allow spoofing, take out the tests for opera and webtv.
    var is_nav     = ((agt.indexOf('mozilla')!=-1) && (agt.indexOf('spoofer')==-1)
                     && (agt.indexOf('compatible') == -1) && (agt.indexOf('opera')==-1)
                     && (agt.indexOf('webtv')==-1) && (agt.indexOf('hotjava')==-1));
								
    var is_ie      = ((agt.indexOf("msie") != -1) && (agt.indexOf("opera") == -1));
    var is_aol     = (agt.indexOf("aol") != -1);
		var is_opera   = (agt.indexOf("opera") != -1);
		var is_webtv   = (agt.indexOf("webtv") != -1);
		var is_firefox = (agt.indexOf("firefox") != -1); 
		
		var cssFile = 'stylesheet';
		
		if (is_nav || is_firefox) {
		  cssFile += '-ns';
		}
		
		document.write('<link rel="stylesheet" type="text/css" href="styles/'+cssFile+'.css"/>');