Admin Themes?

Hey, sorry for being dim. I have a client using a blackish theme, and we’ve run into a problem where they want to reverse out many of their article colors such as white on black, but since the admin editing environment has a white background, they can no longer see the text to edit it.

Is there an official way to substitute in a different admin theme? I don’t want to toy with things and mess them up.

Thanks for the help!