Edit and new SC for 3.12 Sustainable CSS media queries are used

[codewordcreative]

3.12 Sustainable CSS user preference media queries are used

Current:
Success Criterion: Media and preference queries Machine-testable / Resources

Apply the monochrome, prefers-contrast, prefers-color-scheme, prefers-reduced-data, prefers-reduced-transparency, and prefers-reduced-motion CSS preference queries if they will benefit your website or application. Use the print and scripting CSS media queries if they will improve the sustainability of your website.

Suggested:
Edits
Use sustainability-first user preference media queries

Success Criterion - Media and preference queries
Accommodate common user preferences, such as prefers-color-scheme, with corresponding media queries. Consider accounting for additional user preferences, including monochrome, prefers-contrast, prefers-reduced-data, prefers-reduced-transparency, and prefers-reduced-motion preference queries where these will benefit your users. Use print and scripting media queries where these can improve sustainability.

New
Success Criterion – Manually adjustable preferences
Allow visitors to manually adjust the default settings to accommodate preferences without an established preference query and visitors using an unfamiliar, borrowed, public, or locked-down device owned by a third party.

Explanations:
Edits

1. Given how widespread dark mode now is, and the fact that when already in use, it will be more sustainable to respect that, it feels like it should be compulsory for both accessibility and sustainability reasons. Studies show that dark mode alone does not necessarily save energy, as many have their screen brightness turned up to compensate. However, the deed is done if their screens are already brighter - so respecting dark mode preferences still helps. (Do we need measurability data on this?)
2. There is also the considerable benefit of enforcing this part, since it forces devs to think in terms of variables. And once you have variables set up, it's easy to accommodate other user preferences (such as eco mode and accessibility tweaks). It's a gateway to the rest.

New
This has arisen from a discussion on Slack. The benefits here, too, are two-fold:

1. Given the lack of a user preference query for eco mode, this is the only way to support it.
2. Given the prevalence of shared devices and non-regulated internet cafés in many parts of the world, or even grannies who may need to quickly do something with their grandchild's help on that assistant's tablet, it's essential to allow an easy adjustment without diving into settings. Even in sales/showroom situations this can be useful. I would argue all the caveats about the why are necessary, since otherwise people may not grasp the why.

Additional resources:
An article about choosing to use Morphic in a public library:
https://news.lib.uci.edu/libraries-news/assistive-technology-tool-added-all-uci-libraries-public-computers

On accessibility of public computers (more about screen readers, but the same principle applies)
https://eldorado.tu-dortmund.de/server/api/core/bitstreams/a171261b-221b-46b4-8634-5660002938fe/content

A university on ensuring public computers are accessible:
https://www.eiu.edu/adulted/Document%20and%20Accessibility.pdf

Credit: Edited and written by me. Some edits by @TzviyaSiegman. Stronger wording and new SC inspired by discussions with @hidde, @AlexDawsonUK, @tantek, and @systemstree (on the new SC, confirming my impression of how things are in India).