DIV not aligned as expected on Firefox 3.5 (Mac)

URL: http://www.ikebarberlearningcentre.ubc.ca/

The "For student" ,"For community", "For faculty", "For librarian" DIVs are expected to aligned as a 2x2 table.

It works on IE6+, Safari, Chrome and Firefox on PC. But on Firefox 3.5 on Mac, the "For Librarians" DIV is not aligned corrected. It is 开发者_如何学运维still on the left side, but it is blow the bottom boundary of "For Faculty" DIV (in other words, there is a large blank area between For Librarians and For Students DIVs).

Any idea why?

Thanks

I fixed it myself, simply by making each DIV a little bit more wide, and set the same min-height (>= the height of the longer cell in each row).

I don't think it is a perfect fix. I doubt the real back-end issue is how FF renders DIV on Mac. Maybe the defaulting rending (Static) is not about right. Probably "absolute" or "relative"? I don't know.