Another thing I'd like to add: don't override the scrolling behavior. Don't try to "improve" the scrolling by making it "smoother", because while it may work okay on Windows, on Mac, when using Apple input devices, there's a one-to-one correspondence between you moving your fingers on the trackpad or mouse and scrollable things scrolling. These "improvements" usually feel like scrolling through molasses.

In general, don't try to improve browser's default behavior.