$(document).ready(function() {
    /*关闭浮动窗口*/
    $("#aclose").click(function() {
        $("#macji").css("display", "none");
        var divsb = document.getElementById('showbox');
        if (divsb != null) divsb.style.display = "none"; 
    });
    $.fn.smartFloat = function() {
        var position = function(element) {
            var top = element.position().top, pos = element.css("position");
            $(window).scroll(function() {
                var scrolls = $(this).scrollTop();
                if (scrolls > top - 399) {
                    if (window.XMLHttpRequest) {
                        element.css({ position: "fixed", top: 399 });
                    } else {
                        element.css({ top: scrolls });
                    }
                } else {
                    element.css({ position: "absolute", top: top });
                }
            });
        };
        return $(this).each(function() {
            position($(this));
        });
    };
    //绑定
    $("#macji").smartFloat();
});