Different colours on webpage

Hello,

I am sorry if this has been asked earlier, but I am not able to find.

In the provided link, you can see the colour of the blog area is white whereas the site borders are grey-ish in colour. I want to make the entire page area white for all posts and pages.

Please suggest a solution.

Thanks,
Nabiha

The page I need help with: [log in to see the link]