Hi Amy
Please dont take this the wrong way but a really good source of background on stylesheets is at
http://hotwired.lycos.com/webmonkey/reference/stylesheet_guide/
Forgive me if it is a grandma sucking eggs thing
Xcart uses these all over the place so it is really useful to know how to control look and feel through one document such as this. Also it is more compliant with W3C guidelines.