In iWeb, users may want to change the default navigation bar (nav bar) colors and formatting. A google search on the topic shows that everyone seems to think that this is an impossible task, and it took a few hours to figure it out, but it's actually quite easy.
Apparently the code for the nav bar is generated on each HTML page, so you see the code for new NavBar within the CSS definitions for the display of each element of the nav bar. The feed.xml page contains the list of all pages and their URLs to be displayed in the nav bar, and the identifier for that element in the page, but the page itself contains the definitions for how the nav bar is displayed.
So each page can be edited after it is published from iWeb to customize the way the navbar is presented on that page.
This hint will only work for relatively small sites that won't require frequent changes of the nav bar, since the fact that it is defined on each page basically defeats the purpose for which CSS was created in the first place. As it took me a few hours to figure all this out, I am putting this tip out there to help others understand how to do it.
[robg adds: I haven't tested this one.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090527204721587