I don't know much about wordpress but I do know a little about php. It sounds to me you will need to learn a little php to do what you want because it is very likely the php is being used to create the html and stylesheets dynamically. If that is correct what you will need to do is to go in and alter the html/css within the php code and you could very easily break the php by accident. Php is not too difficult of itself, but it can be built up into complex applications like any other programming language. You would probably be better off scouring the wordpress sites and asking their community.
