The “Transparency” and “Combination” buttons are not working for me.

All the buttons in that area require not just a click but holding mousedown for effect to occur, Transparency and Combination work for me in Firefox if I do that.

Oh, right, I see. They do work. It was not obvious that you have to hold down the button.

I modified the animation so it starts much more quickly.

If I made them instantaneous, then a quick click would be enough but it wouldn't really be an animation — it would just be a state change.

If I made the animation start with a click, then I'd have to have a reset button.

This seemed like a good compromise, although it's true that a few people were confused.