I know bits and pieces of CSS well, and large swathes barely at all. Since I'm reading this via gmail, and it has a similar layout except it resizes nicely, I did a quick Firebug check to see how they do it.
I would never have guessed. They do exactly what you're doing: use absolute numbers of pixels. But when I resize, they apparently do Javascripty magic to rewrite those numbers for the new screen size. Tricksy hobbitses. Want to try doing the same? Seems far easier than doing "real" resizeable layout.
