I don't know if this is a reply, or if it is on topic :-)

Using tables for layout is pretty much standard, though ugly.

Using css for font styles is fairly well supported, degrades nicely
(stuff is just in another font), and is very convenient, especially
when combined with using tables for layouts.

Stuff that doesn't work as well: positioning via css(dHTML), pseudo
classes in css like a:hover, scripting plugins.  There's more stuff on
that list, but it's scared me so bad I've blanked it from my memory. 
Actually, you can do alot cross-platform, but your debugging time
really goes up as you try to find the exact combination that works
over your target browsers.

Here's an example of something that took forever:

http://www.creativemediaphd.com/home.html

The site was built via a ruby script that merges content html files
and images and generates a single long file.  This was to satisfy two
requrements: so the page wouldn't 'blink' when someone clicks on a
link in the flash movie, and so that the admin can edit the site in
html.

Let me know in an email how it works on linux, or if you find a bug
:-)

~ Patrick