Removing whitespace beneath footer with CSS (Wordpress)

I just revamped my website and I'm having a bit of trouble with the fine details (keep in mind that I know almost nothing about web development, even though I'm in the software field; I'm trying to learn).

Namely, I noticed on some of my smaller pages (my About page, for example) have a white bar going across the screen underneath the footer. I'd much rather have the footer dynamically extend itself to the bottom of the screen. How can I do this, can I write some custom CSS?

Here's my site: http://ift.tt/1PymGz6