[awj]

I like the general concept, but I think it relies on specific behavior to the point of being confusing.

* As others have mentioned, there's no advertising of accepted cards

* None of the empty inputs look like inputs until you tab into them. They also cease looking like inputs when you tab out. Correcting data that is not objectively invalid (e.g. expiration in the future, but wrong month) is kind of unintuitive. Someone who clicks into form fields will likely be entirely stumped by this form.

* It doesn't seem to work on mobile. On my iPhone the series of inputs were positively irritating to interact with, somehow each one only took three characters instead of four, and the lack of a tab meant I had little direction on where to go when the first four digit input disappeared.

* The CVV is clumsily poorly handled. You can actually tell in that you're breaking away from skeuomorphism to get the user to that input. It might be a better idea to show the "back" next to the card when you do the initial breakout.