Toggling CSS animation with JQuery on iBook

I've created a sprite animation on a page using CSS animations, and using JQuery I toggle on the animation so it stops and restarts as you tap. It all works as it should, however, when I tap on the animation there's a gray overlay the size of the animation that appears briefly as I tap on it. How can I stop that from happening?

Or is there a way to stop and restart an animation using CSS only? I think that would solve it, just don't know how.

Thanks

JD