Currently, Dark Mode changes the UI, but not the document area, which is most of the app. Consequently, Penbook is more comfortable than GoodNotes when I want to scrawl out an idea I woke up with at 3AM.

RGB color inversion usually looks terrible, but preserving hue and saturation while inverting luminance (brightness) in HSV space typically preserves contrast and color-coding while providing the sentiment of “dark mode”.

Could luminance inversion in the document display area be an option for Dark Mode?