lucy24 - 9:38 pm on Mar 1, 2012 (gmt 0)
What we may really need is the site structure. CSS doesn't "carry over"; each separate page has to specify the style sheets it uses.
Do the pages use relative links or site-absolute links to call those style sheets? If you've got any combination of rewrites and relative links, then mixed-up CSS may end up being the least of your problems. Same if you're using dynamic pages where the same header code is recycled for different directories, especially for different directory levels.