This site could be a real saviour, can't believe I haven't found it before!
I am trying to edit the style sheet in twenty eleven in WP to get the menu to do something specific.
I am at the very beginning so there is no content, and the actual style isn't even set - I'm just trying to get my head around things.
The site is here.
Ok at the moment on the active page, the menu has the image with the black and white checking on it - this I was able to work out pretty easily and the styling is: