var agent = navigator.userAgent;

        var appver = navigator.appVersion;

        var nav = navigator.appName;

        var plf = null;

        var ver = null;

        if(agent.indexOf('Mac') != -1){

                plf = "Mac";

        }else if(agent.indexOf('Win') != -1){

                plf = "Win";

        }else{

                plf = "other";

        }

        if(agent.indexOf('MSIE') == -1){

                ver = appver.charAt(0);

                if(nav == "Netscape"){

                        nav = "Netscape";

                }

        }else{

                ver = agent.charAt(agent.indexOf('MSIE') + 5);

                nav = "MSIE";

        }

        var ms = navigator.appVersion.indexOf("MSIE");

        var ie4 = (ms>0) && (parseInt(navigator.appVersion.substring(ms+5, ms+6)) >= 4);

        var winie4 = (plf == "Win") && (ms>0) && (parseInt(navigator.appVersion.substring(ms+5, ms+6)) >= 4);

        var macie5 =  (plf == "Mac") && (ms>0) && (parseInt(navigator.appVersion.substring(ms+5, ms+6)) >= 5);

        var nesc = navigator.appName.lastIndexOf("Netscape"); //一致した位置(0)を返す

        var nesc4 = (nesc >= 0) && (parseInt(navigator.appVersion.substring(0,2)) >= 4);



        var MacMozilla =  (plf == "Mac") && (nav == "Mozilla");



    if (plf == "Mac" && nav == "Netscape") {

    document.write('<LINK REL="stylesheet" TYPE="text/css" HREF="../css/mac_nn.css">');

    } else if (plf == "Mac" && nav == "MSIE") {

    document.write('<LINK REL="stylesheet" TYPE="text/css" HREF="../css/mac.css">');

    } else if (plf == "Win" && nav == "Netscape") {

    document.write('<LINK REL="stylesheet" TYPE="text/css" HREF="../css/win_nn.css">');

    } else if (plf == "Win" && nav == "MSIE") {

    document.write('<LINK REL="stylesheet" TYPE="text/css" HREF="../css/win.css">');

    }