JQuery根据滚动位置和窗口宽度动态添加/删除类

I want to add/remove a class based on scroll position AND window width. The class should be added when the user scrolls vertically past X AND the window width is larger than Y. If BOTH conditions are not met, the class should be removed. If the user scrolls back to the top, the class should be removed as well. I want to add/remove a class based on scroll po