I've compiled what I hope is a complete list of the classes and ids used within the guide, and their purposes (in most cases obvious, but it is helpful to have a complete record).
It's temporarily at http://www.ox.compsoc.net/~dom/openguides-patches/README.CSS - I'll either commit it to CVS in that form or incorporate it into the comments in a plain CSS file to be distributed as a default file.
Until I do this it would be helpful if developers could ping me of they make any changes that would affect this file.
It may be useful for you to check that your CSS is consistent with this list (assuming of course that you are running the CVS codebase - a few changes in classes and ids have been made this weekend not yet released).
Cheers,
Dominic.