Allow full branding of ADFS login page, not just an image/title
Please provide more details on the kind of customization you would like to achieve with the ADFS sign-in page as well as the version of ADFS you are using.
Omer Cansizoglu commented
Some customization ideas that will be needed:
1- Background color
2- Message section below the login section to alert/announce something such as maintenance to your own system.