Here you can define the appearance of the user login page.

The headline is displayed below the logo.

A corresponding logo can be specified here via an absolute path.
The logo can be uploaded to the system in “System” under “Settings” -> “Image upload”.
After uploading, the exact url is displayed. This can be used here.

A background image can be set in the same way as a logo.

The background color can be set from a color selection dialog