I'm not talking about office themes, I use the black theme for all of my office apps, and it's great thanks. I understand why the only options right now are light colors, but I would really appreciate an option to set a custom color, for those of us who live for dark mode. If office doesn't want to deal with issues supporting this, it could be buried deep in settings somewhere, or could disable sharing templates with custom colors.
I really like office, but I need a grey background for all of my Onenote pages.
(I tried setting an image to background, it was not useful)