Braintree Hosted Fields
braintreepayments.com
braintreepayments.com
As opposed to Stripe.js where the credit card inputs in a custom designed form live on the merchant's DOM, Braintree just set it up so that it replaces each field with an iframe (that also allows for custom styling), so that the credit card info gets entered directly to Braintree despite it looking like your own page.
Awesome Braintree!