Pretty severely broken on Firefox: can't type in a card number, and the "Fork me on GitHub" banner is missing. That second problem is particularly weird, I don't know what could be causing that. Also wondering if jQuery is really necessary for this.<p>Overall, it's a nice concept. I wish checkout forms were more intuitive.
For a production ready alternative, take a look at <a href="http://creditcardjs.com" rel="nofollow">http://creditcardjs.com</a>, which was posted on HN a while back. The web site points out common mistakes when implementing credit card forms and delves into the motivation behind every design decision.
You should be able to type "2/16" in the expiration, but instead when you try, you end up with "21 / 6".<p>I'm still amazed at how sites that can't handle spaces or dashes in the card number or want it formatted in 4 different text boxes. The actual card number worked very well on your form.
How about making the placeholder text lighten up a bit on focus.
Something like this for webkit should work<p>:focus::-webkit-input-placeholder { color: #eee;}
this is great but I like to use <a href="https://www.paymentiframe.com/" rel="nofollow">https://www.paymentiframe.com/</a><p>the form resembles a credit card.