How to Detect Browser's site-specific Dark Theme?

[kofaysi]

I would like to apply changes in user.js based on the browser's site-specific Dark Theme setting. My goal is to adjust site behavior dynamically based on this theme setting.

However, the common method of detecting the theme preference:

window.matchMedia('(prefers-color-scheme: dark)')

is not sufficient, as it only detects the operating system's theme preference and not the browser's site-specific theme setting.

Could you clarify:

1. Are there any attributes or methods in Chromium that can directly detect the site-specific Dark Theme setting, independent of the OS preference?
2. If not, is there any workaround or strategy you would recommend for dynamically adapting behavior based on this setting?

Any insights or guidance on achieving this functionality would be greatly appreciated.

Thank you!

[uazo]

is not sufficient, as it only detects the operating system's theme preference and not the browser's site-specific theme setting.

I can't answer your questions, I have never yet read that part of the chromium code, I know where it is but I have never looked into it.
one of my goals is not to allow the detection of user or system settings, therefore, the aim is not to make it possible.
the fact that you do not detect it, however, is interesting.

Any insights or guidance on achieving this functionality would be greatly appreciated.

try looking at the official tests https://wpt.live/css/mediaqueries, the ones starting with ‘prefers-colour-scheme’.

[kofaysi]

FYI All Most of the prefers-color-scheme test passed.

Edit: Sorry, I guess I have found one which does not play as intended:

That is, site-specific theme is light (not dark), but the script detects dark. My Android theme is dark.

When my Android theme is light, the script test works as intended:

Now, I cannot even switch to dark theme in the browser. Huh?

With Android light theme, I switched chrome://flags/#enable-force-dark to ON and I could make the test fail the other direction;

I do not understand the behaviour yet.

[uazo]

interesting, thank you!