Parallax problem

I like this theme but I am having issues with the parallax areas.
While scrolling the background image will bounce outside the parallax area on the home page. So the image is brighter as it’s not sitting under the overlay .athena-footer > div
I thought this was a problem I created until I tested your demo version in all browsers.
The same problem is there in opera and chrome but not as bad as firefox, safari and ie.

Thanks