Footer Widget Area

I’ve created a child theme of twenty thirteen and I’m having trouble with the footer area. I have set up a recent posts widget in the sidebar widget area at the bottom, but for some reason the background colour of that area only extends halfway down, and then the site generator area pushes up and is displayed halfway up into the footer.

I know that setting a min-height for that area would fix the problem, but I want to potentially sell this child theme, so I need it to work for everyone, and setting a min-height would only work for the content I can see (as others might add taller content).

I have also found that #secondary {overflow:hidden} does the trick, except when I load the page and scroll to the bottom, i only see half the images in that section and the bottom half of the footer area is hidden. But if I grab the window and scale it bigger, it looks perfect. but every time i load the page again, it does the same thing. Any thoughts??

My site is here.