Grey Background - Unable To Change

I've had an ongoing issue with a grey bar displaying on my site.

I think I've been able to resolve this as an issue, but still have a situation where when you scroll to the limits of the site you get a motion effect where there is still a grey space appearing. 

It's not the end of the world, but i'd prefer it didn't happen.

In the site styles, as far as I can see, I've got everything set to black that should be. Any advice massively appreciated.
 

Hi,

Can you share link to page where you have problem? We can check easier