There's been many complaints about skinning/designing for SharePoint, and while some complaints can be debunked it's hard to argue that MOSS is not a mess, from an HTML object hierarchy standpoint.
On a random content page, here is the path to the main content:
body > div > [table > tbody > tr > td] > [table > tbody > tr > td] > div > div > [table > tbody > tr > td] > [table > tbody tr > td] > [table > tbody tr > td] > div > p
According to Firebug, that poor paragraph tag is acted upon by no less than 12 - TWELVE - style sheet rules... Debug that!
(This is not a rip on InfoCision's webpage - it's a nice example of customizing SharePoint's masterpages and themes to get a custom look and feel.)