Min-height=100% not working for main body text

The page in question is here – The CSS file is here. It’s all dummy lipsum till it’s right, then I’ll move it to its own domain and import old posts. Which is why it looks that way.

I’ve given the various sections colorful borders to make it make more sense. The main body is bordered in blue. I want it to take up all the available space, pushing the footer to to the very bottom of the page. In my styles.css file, I’ve told that section to be min-height=100%; it absolutely does not respond to that in any way. However, if I change it to: min-height=495px; (495 is an arbitrary example) it DOES behave right.

(I don’t WANT it to have a min-height of 495 or any other arbitrary number; I want it to be 100% so it looks right on any screen.)

I’ve been beating my head against the wall on this one, and would really appreciate any help anybody can give. Thanks for reading.