We print everything on our 100% post-consumer recycled white matte paper. Designs that appear to be on a different paper color use ink to print over the entire card, so we can certainly print any desired color you want on our even if the design you're using has a white background. Just request Free Designer Assistance to add a custom color after personalizing the rest of the card.
For other design-related questions, please contact us and our support team will help you understand all your options.