[wxMaxima] Dark mode - wxMaxima-developers/wxmaxima GitHub Wiki
If wxWidgets is new enough wxMaxima will automatically be in dark mode if the rest of the operating system is.
The worksheet itself is by default equipped with a bright background.
But it can be configured otherwise.
Alternatively there is a View/Invert worksheet brightness
menu entry that allows to quickly convert the worksheet from dark to bright and vice versa.