Get direction UIWebView is scrolling

Question

Hey! I need to find a way to keep my page's bounce scrolling looking good. Here's what I need:

When the user scroll past a UIWebViews scrollable area (top), the background color of the view should be set to [UIColor colorWithRed:0.839 green:0.871 blue:0.871 alpha:1.000] and when the scrollable area is drug too far on the bottom, the color of the view should be set to [UIColor colorWithWhite:1.000 alpha:1.000]

Don't worry about the view being opaque and all that, becaue I've already done that in my code.