if (navigator.userAgent.indexOf("Mac") != -1) {

    if (navigator.appName.indexOf('Netscape') != -1) {

        document.write("<link rel='stylesheet' href='/css_js/mac-ns.css' type='text/css'>");

    }

    else {

        document.write("<link rel='stylesheet' href='/css_js/mac-ie.css' type='text/css'>");

    }

}

else if (navigator.userAgent.indexOf('Win') != -1) {

    if (navigator.appName.indexOf('Netscape') != -1) {

        document.write("<link rel='stylesheet' href='/css_js/win-ns.css' type='text/css'>");

    }

    else {

        document.write("<link rel='stylesheet' href='/css_js/win-ie.css' type='text/css'>");

    }

}

else {

    document.write("<link rel='stylesheet' href='/css_js/win-ie.css' type='text/css'>");

}
