Animations

If you're going to use animated images, I suggest you use .gif extension.

Am I breaking a rule?

I didn't want to use .gif because it's limited to a tiny color palette and would probably have looked horrible.

Firefox and Opera will display the animation, browsers that don't support animated .pngs will just show the first frame statically.

The filesize is small enough, and I don't really need more than one picture, so...

No rules were broken. Just a mere suggestion. It's alright if you wish to use your .png.

Okay, thanks. I'm probably going to leave it the way it is. :P