In the system, you can easily create new branded buying processes and design them according to your own graphic profile.
Navigate to Administration - Integrations - Skin.
To edit existing skins, tap on their line or on Actions - Edit. If you want to create a new one, press Add skin on the right.
Here you can now edit colors, upload new images and edit the purchase process's CSS file. Note that editing CSS is at your own risk and you must take responsibility for the design of your branded buying process if you choose to go this route.