Its a cool demo but technical speaking its nonsense to use CSS for this. It should have been made with SVG, or a similar kind of technology. There are enough vector renderers for example the canvas element if there is no SVG support.
With this CSS map a user could customise the colour/pattern of just a couple of problem lines (I could already in Firebug, but it would be great if there was a control panel to fiddle these things and then provide print/save links). Just an idea!
Codewise it's cute, but functionally wouldn't a canvas element make more sense than a couple of hundred list elements?
There are also restrictions over the font, logos and symbols.
But where does the copyright infringement start? Could you technically get around it if you changed a couple of the colours and fonts around and used slightly different angles?
It might result in a few confused travellers, but hey.
Naturally this CSS map is an almost 1-for-1 copy of the original. But how far would it have to diverge to not be copyright infringement? Different colours? Use rounder angles ?
But I never took the time to finish it.
"Regrettably I have decided to take down this project whilst I investigate licensing rules regarding my use of the Underground Map which is owned by Transport for London."
I don't know what they did to the PDFs but they take 3 seconds to render on my modern laptop, and do not work with some opensource readers. Try it yourself.
I'd be more likely to refer to this map now than the official PDF, so it's nice that it has a memorable URL.
To the OP, don't people in the UK use facebook? Add a like button.
And the tweet button is taking the current url so on your info page it shows 0 tweets (you might want to change that)