Doesn't work in FF2.0 (unsurprisingly). BTW: a nice thing about xkcd's drawing is that the heads are slightly off-circular, to imply direction, tilt of head, a

Doesn't work in FF2.0 (unsurprisingly). BTW: a nice thing about xkcd's drawing is that the heads are slightly off-circular, to imply direction, tilt of head, and some cases even expression.