javascript修改div大小遮挡页面渲染问题

   window.onresize = function () {
           
            var w = $(window).width();
            var h = $(window).height();
            var Menu_w = $(".SystemMenu").width();
            var Head_h = $(".SystemHeader").height();
            var RightBox_w = w - Menu_w;
            var RightBox_h = h - Head_h;
            $(".SysRightBox").css({
                "width": RightBox_w,
                "height": RightBox_h,
                "right": RightBox_w
            });
        }