The only branding options currently available in GIM are on the Administration -> Preferences -> Look and Feel tab.
At this time the only modifiable options are the sidebar banner (and collapsed image) and the application text. There is no per-portal modifications you can make, as these are globally shared between admin, provisioner and self-service provisioner pages.
![68a2691acd414d81946e24f161909899_940aaabf-1f23-4967-89c0-06b5493b9a76.png 68a2691acd414d81946e24f161909899_940aaabf-1f23-4967-89c0-06b5493b9a76.png](/t5/image/serverpage/image-id/1212i5D678018B9E92705/image-size/large?v=v2&px=999)
If you're using NAC (Access Control Engines), you can get more granular with the self-registration configuration on the NAC portals in XMC, with color palettes and header/footers, etc.