lucy24 - 9:05 pm on Feb 22, 2012 (gmt 0)
You can get a lot of information simply by giving each of your css classes a border of some kind: red solid here, blue dotted there, et cetera. Then you look at the page and say "wtf? There's not supposed to be any padding there!" It isn't a foolproof trick, because the border itself adds one px to everything. But it's an easy test.
Anyway, that extra container explains why the two tables looked identical on all my browsers. They were identical!