CSS to make HTML page footer stay at bottom of the page with a minimum height but not overlap the page

Question

I have the following page, which contains a footer that I can't get to appear at the bottom of the page (deadlink: http://www.workingstorage.com/Sample.htm).

The footer should

When the page is brief and the screen isn't full, stay at the bottom of the window; when there is more content than can fit on a screen, stay at the document end and slide down normally (instead of overlapping the content).
I don't understand the inherited CSS. I'm unable to make the footer go all the way to the bottom or set a minimum height for the content.