Ahh, CSS- I love you.

Live, in a browser, entirely CSS- only image is the plus icon.

Using:
* border-radius
* rgba
* text-shadow
* box-shadow
* background-gradient

I'm particularly happy with how well the shadow gets faked on the current tab. The other tabs could use a bit more polish, but they're looking pretty good, overall.

Working with a client that fully gets and supports progressive enhancement is really rewarding. Andy Clarke would be so proud... *sniff*