Option to select light/dark mode is OK backend, but that’s not convenient enough.
Please add an option to respect OS and browser preferences (“auto”?), and add a toggle inside the builder so that we can switch easily between auto/light/dark.
That’s a totally different story.
The darkmode of the builder has nothing to do with the frontend.
Each darkmode has it’s own requirements. That’s not a simple toggle.
No real white, no real black, different font weights, differenz bordersizes, image reworking (Brightness / saturation) and many more.
The whole design draft decides if you’ll get a well working darkmode or not.
You can use oxy (Bricks) Props - that framework give you the colorsystem and a toggle.
Not sure about the also necessary code for saving the user preference to local storage.
If you only use prefers-color-scheme you maybe don’t need it.