While its cool demo of what CSS can do... The reality is: CSS is not meant for this.
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.
Could probably ensure it fits in the window nicely though, with zooming etc. Seeing only the North-West of London on screen without scrolling is not as useful. I'd imagine it's damn hard to use on a laptop without two direction scrolling. Functional over pretty, I vote :)
This could actually have a very helpful application- generating maps with customised colour schemes. Anyone with a form of colour blindness will know that some of the lines on the standard map are basically indistinguishable from each-other, and while TfL does provide a black-and-white map, it's designed for ALL forms of colour blindness, so they've had to come up with a load of different patterns, making it a bit messy (http://www.tfl.gov.uk/gettingaround/14091.aspx).
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!
I suppose the main thing you'd need is a data source mapping the stations and lines, then build it in whatever technology from that. The information page doesn't mention where the data came from, so I imagine it was manually created. I don't think TfL would be too willing to provide that data either, judging by the comments regarding licensing etc. in this thread.
I have seen people get around it by making their own version of the map. Those maps usually end up having the stations match their respective locations to each other more closely. They naturally don't look as 'good' as the official map though.
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?
So in other words, the author of this and the original post is really good at using the wrong tool for the job. I think it would greatly increase his credibility if he would mention that this isn't what CSS is meant to be used for and is just doing it for demo purposes. Too many people seem to get the impression that CSS should be used for actually drawing things.
Who is getting that impression that css is supposed to be used this way? It's meant to show what is possible. That's it. I think it's already absurd that most of the posts here are dog piling on the creator for "using the wrong tool" but to say it decreases his credibility for not mentioning this is not what css was meant for? That's just plain wrong in my opinion. It's a fun thing, let it be what it is.
Our map changes 3-4 times per year for new stations / closures etc so supportability of something like absolute CSS locations would never fly. Fair play for giving this a go though, it's pretty darn accurate and super quick!.