I think you need to also set any wrapper elements inside of the body to min-height: 100%.
I set section#main{min-height: 100%} to get this to work.
In case you aren’t already doing it, you can try these kinds of things inside of your browser’s web inspector. On Chrome, right click on a page and select ‘inspect element’. It’s a lot easier if you have 2 monitors, You can detach the inspector window and have enough room to see what is going on and try things out.