This epic will contain tickets related to explorations around dark mode and other palette customizations for desktop and mobile web. The hypothesis is that persistently introducing palette customizations will lead to a significant improvement in the quality of the reading experience across the desktop and mobile web, especially for users with visual impairment and sensitivity (see T341631: [EPIC] Q1 Main hypothesis: Typographical and palette customizations)

Sequencing

The following sequence assumes that as part of font size we have built the control for user's to modify their preferences and instrumentation is in place. When implementing the dark mode feature flag, the control will appear in the interface and be fully instrumented without any further work.

The following milestones needs to be done in the following sequence to ship a beta feature:

• Kick off community consultation 1 to get input about content. This will include results of performance analysis of dark mode (T349308). [Szymon and Jon]
• Add dark mode feature flag/user (client) preference.
• Add instrumentation to detect article problems in dark mode so that we can assess whether dark mode is "ready" and guide community members on high priority issues to fix (T350030 spike and implementation follow up).
• Express skin background color and color variables in CSS custom properties
• Several theming colors are defined in MediaWiki core - make
• Update key components from other teams to work in dark mode ULS (T340255 ), Codex, Echo [This could involve expressing these in CSS custom properties or could involve applying a temporary solution e.g. invert hack)
• Close out community consultation 1. Implement content dark mode policy taking into account feedback from community consultation. This may involve additional configuration.
• Ship to beta features on all projects.
• Community consultation 2 - identify broken templates and work with editors to fix them.
• Ship to production.