1792672 - Support `prefers-constrast` media query on Android

Status: NEW

(GeckoView :: General, enhancement, P3)

Description

[Chris Peterson [:cpeterson]]

prefers-contrast:more activates styles that web authors have specified for users who prefer increase contrast, improving the overall web experience for these users.

Morgan Reschenberg says desktop Firefox activates prefers-contrast:more when:

• macOS's "Increase Contrast" setting is on.
• Or Windows' high contrast mode setting is on and the ratio between the foreground and background colors is more than 7.
• Or Firefox's high contrast mode is on and the ratio between the foreground and background colors is more than 7.

We need to figure out how the high contrast settings on Android operate to know whether it should fall into the prefers-contrast:more category. Depending on behavior, we may find forced-colors more appropriate.

Mozilla Hacks blog post about adding prefers-contrast support to desktop Firefox:

https://hacks.mozilla.org/2020/07/adding-prefers-contrast-to-firefox/

Comment 1

[Chris Peterson [:cpeterson]]

Fenix would not need new settings UI for high contrast mode. Android has system settings for high contrast display mode and color inversion that can query, though I'm not sure which system settings should control prefers-constrast. It might be different depending on the Android OS version.

https://support.google.com/accessibility/android/answer/11183305

Comment 2

[Morgan Reschenberg [:morgan]]

This is a separate question, but I wonder if we should enable backplate for users who have high contrast text enabled in their android settings... 🤔

Comment 3

[Chris Peterson [:cpeterson]]

Tasks and enhancements should have severity N/A.