Structuring CSS and naming conventions


I would be really interested if there is any convention or strategy to
help with CSS in Rails.

Currently my styles are in a couple of fairly large stylesheets and I
use the single application layout throughout. (I like a consistent
pages for my whole app)

However, I find naming styles a constant struggle. The stylesheet has
become unwieldy and I struggle to avoid name conflicts. (I find this
with CSS generally anyway)

I am thinking that I should start to have different stylesheets for
different areas of the app and one for common functions, then the
different stylesheets need to be loaded. What is the best way. I am
reluctant to use different layouts because that would not be DRY. I
could use content for to pick up the different stylesheets, but that
seems a bit messy.

also what about performance, if I keep changing stylesheets, would
they still be cached by the browser (Firefox in my case).

Finally what about naming convention. I am rapidly coming to the
conclusion, that the best approach is to have a main div for each page
with an id of the controller-action. Then id's in that div could be
simple and need not clash as long as I always target my rules using
div#name-controller div#something etc { css rules }

This starts to feel a bit more structured like the rails app. But am
I over doing it? It seems to me there must be a generally "best" or
pragmatic or agile way to do css stuff. I just cant see it. So maybe
those of you who have been doing this for large apps could give some