监听滑动条滚动事件，当接近底部导航时隐藏

$(window).scroll(function(){

        var topp = $(document).scrollTop();

        var page_height = $(document).height();

        var instance = page_height - topp;

        if(instance < 1250){

            $(".make-sidebar").css("display","none");

        }else{

            $(".make-sidebar").css("display","block");

        }

    })