Feature summary (what you would like to be able to do and where):
Since ContentTranslation uses its own skin, it doesn't support dark mode out of the box. Minerva and Vector 2022 support a dark mode theme using a class on the HTML element skin-theme-clientpref-dark / skin-theme-clientpref-os the value of which comes from a preference minerva-theme / vector-theme or by using mw.user.clientprefs.get('skin-theme'); for anonymous users.

Suggestion

• For anons: ContentTranslation adds a class skin-theme-clientpref-day to the HTML element. This should allow it to benefit from any cookie that has been stored on the device.
• For logged in users: Either ContentTranslation should have its own dark mode preference, or should read the preference from Vector 2022/Minerva.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

• Some users prefer using a dark mode.

Benefits (why should this be implemented?):

• Consistency with the rest of the site