Designing for BTCPay Server consists of improving overall experience for the end-user, making it easier to navigate the menus, options, etc...
To contribute design to BTCPay Server, check out the UX/UI channel for current discussions and the Figma getting started section for the design projects that are currently being worked on.
Graphic content also helps promote BTCPay Server. Be it full scale logos, memes or other graphics, we're always enjoying seeing what contributors come up with. Following the Codified Design Guidelines is required so that graphical content can be consistent between contributors.