Light/Dark toggle doesn't work with -dark stylesheets

[cassidyjames]

I think WebKit is looking for a -dark suffix in addition to a :dark theme variant, so the web styles are forced to always be dark. I see two options:

• Hide the toggle if the current stylesheet is -dark (easiest), or
• Show the toggle but have the light version request a stylesheet with -dark stripped

The latter has potential breakage, i.e. if there's an installed stylesheet called, foo-dark but not one called foo. In that case it will fall back to Adwaita, which is still probably fine. I believe this is a similar approach WebKit is taking for native input styling.

This directly affects Ubuntu 20.04 with their light/default/dark setting, as well as Pop!_OS (maybe since 19.04 or 19.10?) with their dark mode toggle that forces pop-dark.

[p1u3o]

The latter has potential breakage, i.e. if there's an installed stylesheet called, foo-dark but not one called foo. In that case it will fall back to Adwaita, which is still probably fine. I believe this is a similar approach WebKit is taking for native input styling.

I think Firefox might do this now too.

[cassidyjames]

Ugh, after spending way too much time poking at this, everything is terrible. I tried to get things to work with option 2 above, and it breaks being able to change the theme on Ubuntu after opening the app. I think I'll just implement the first option and drop the switcher if the OS or user is using ugly dark mode hacks.

[cassidyjames]

Both have been spiked out as PRs #233 (to hackily try to support -dark themes), and #234 (to hide the switch when using -dark themes).

Not sure which I am in favor of. #234 is certainly simpler.