Here's some text just to act as the header without adding additional divs

The side containers are explicitly set in width and outlined in red to show their boundaries. As expected, they float quite happily where they should.

However, you can see a problem already. The container div is taking up the whole page. So what happened to the left and right margin I asked for?

W3schools.com says "The CSS margin properties define the space around elements." I just defined the element, so where's the margin? I think that is what is causing the issue--it's ignoring that I said I wanted the div to have a margin. When you are floating something above it, that's no big deal, but it wreaks merry hell with the stuff in the center if you try to set a width for something in it.

This is the block content

Block content is a wonderful thing becasue after all, the purpose of blocks is for showing content. Right?

Right.

Right block column

This is the center body content. Text alone works just fine.
But add the table....

I am a table set to 100% of the container element

Add "overflow: hidden;" to body_content_center in css and the table renders correctly--it doesn't get clipped. But if there was overflow, why wouldn't it get clipped?

I hope this helps to show the problem clearly.