Is it possible to change the background of a Content Library Notification?

Summary:

See screenshot … customer is complaining about this Redwood looking background. They would rather have plain white or something else. Can it be modified? There is also a lot of open space at the top before the actual message starts.

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

25C

Code Snippet (add any code snippets that support your topic, if applicable):