$(document).ready(function () {
    $("div.mainmenu_item").hover(
            function () {
                $(this).css("background-image", "url('/NewImages/default_header_menu_bg2.jpg')");
            },
            function () {
                $(this).css("background-image", "url('/NewImages/default_header_menu_bg1.jpg')");
            });

    $("div.mainmenu_item1").hover(
            function () {
                $(this).css("background-image", "url('/NewImages/default_header_menu_bg4.jpg')");
            },
            function () {
                $(this).css("background-image", "url('/NewImages/default_header_menu_bg3.jpg')");
            });
});

        function ShowRegister() {
            $("div#login_title").html("<div style=\"float:left\">用户注册</div>\n<div style=\"float:right\"><a href=\"javascript:ShowLogin();\">取消</a></div>\n<div class=\"clear\"></div>\n");
            $("div#login_txt").css("display", "none");
            $("div#register_txt").css("display", "block");
        }

        function ShowLogin() {
            $("div#login_title").html("用户登录");
            $("div#login_txt").css("display", "block");
            $("div#register_txt").css("display", "none");
        }