function select(show, hide) {
        var btn_show = document.getElementById('btn_'+show);
        var login_show = document.getElementById('login_'+show);
        var btn_hide = document.getElementById('btn_'+hide);
        var login_hide = document.getElementById('login_'+hide);

        if(btn_show) {
            btn_show.className = "";
        }
        if(btn_hide) {
            btn_hide.className = "btn_hide";
        }
        if(login_show) {
            login_show.className = "";
        }
        if(login_hide) {
            login_hide.className = "login_hide";
        }
    }