if (parseInt(navigator.appVersion) >= 4) {
        var IE4 = (navigator.appVersion.indexOf("MSIE") > 0);
        var NN4 = (navigator.appName == "Netscape");
        var OS;
        if (navigator.appVersion.indexOf("Win") > 0) OS = "Windows";
        if (navigator.appVersion.indexOf("Mac") > 0) {OS = "MacOS";}
        switch (OS) {
            case "Windows":
                if (IE4 > 0) document.write ("<LINK href='/urbanforum/includes/css/ie.css' rel='stylesheet' type='text/css'/>");
                if (NN4 > 0) document.write ("<LINK href='/urbanforum/includes/css/nn.css' rel='stylesheet' type='text/css'/>");
                    break;
            case "MacOS":
                if (IE4 > 0) document.write ("<LINK href='/urbanforum/includes/css/iemac.css' rel='stylesheet' type='text/css'/>");
                if (NN4 > 0) document.write ("<LINK href='/urbanforum/includes/css/nnmac.css' rel='stylesheet' type='text/css'/>");
                break;
            }
        }