calculating widths depending on margin, div, padding

[update]

Hi all,

I'm trying to set up a new site relying on div and css (what an adventure )

Now I got stuck in calculating the widths of page and different elements (divs). It seems that all these browsers out there are handling this in a different manner (to check it I use Firefox 1.5+, Opera 8+, Netscape 7+, IE 6+, avant 10+) .
Am I going to be forced to use different style sheets and a browser detection or is there a simpler way to handle this? How do you deal with this one?
Any help is really appreciated!
Many thanks in advance!

Greetings
claus

[Ren.Hoek]

Hi,

oh yes, this _is_ a pain in the a**!
Therefore, there a loads of websites dealing with hacks, types of browser detection and so on.

Me personal, I tend to create layouts where it doesn't matter that much if the div... is some pixels different in size. ("floating...")

Quickly chosen further reading:
http://www.alistapart.com/articles/
http://www.css4you.de/
http://virtuelvis.com/archives/2004/02/css-ie-only
http://tjkdesign.com/articles/branching.asp

Greetings, Ren Hoek