一旦滚动过特定的div，就隐藏div

I have a slideshow that has a height set to auto so any height image can be displayed. Within that slideshow I have two arrows which are wrapped in a div with a class of .center. The arrows are at a fixed position so when scrolling the arrows would follow. The function that is assigned to div="center" will display when you scroll over the div .center. I have a slideshow that has a height set to aut