Hold footer on bottom

I'd like for the home page to only show top-header if user is not loggedin.

I am able to do this, however, the footer is right below top-header and there is a lot of white space below footer.

I'd like to fix the footer to the bottom of screen at all times.

I was successful in doing this however when I minimize the screen, the footer is now on top of top-header div.

Any CSS geniuses out there?

How can I fix the footer to the bottom but be fluid enough to not go on top of the top-header but stay below it.

I'm on my staging site: http://lam.staging.wpengine.com/

I'd also like for the background to go all the way down to the footer of top-header.

Thank you!