Tap feedback overlay glitches

When pressing a key there's feedback in the form of a larger version of the key, which is (in most cases) displayed above the key. While this could be useful in practice, the current implementation is quite glitchy and probably worse than no such feedback.

Current issue include

• For keys in the top row the overlays is displayed under the finger, and therefore useless (I assume this is because it can't be outside the keyboard's boundaries?)
• It's blue, which draws too much attention (and the pressed key is also blue, which is also not great). I'd make both of them a ~30% lighter version of the normal key styling
• The shapes/proportions of the overlays are weird, and need proper design (it looks like they're the same as the regular keys, but scaled up)
• The overlays should only appear for normal letters/numbers, not for space, delete, enter, etc.

Unless we can fix these I'd disable the overlays for the coming demos.