This is a parent ticket for what is often called "night mode" but actually covers several customization features to increase/improve reading comfort. This broader use case set is called "reading themes".

This is 1 of our 2 most requested features and we believe its implementation will increase long term retention and reading times for frequent/heavy readers of Wikipedia.

High level requirements:

• Allow user to chose a color scheme for the articles and app chrome, including, at minimum themes for low-light reading (night mode) and our existing official app theme (paper white?). Additional themes, particularly a sepia theme to reduce eye strain, are also in scope, but secondary priorities.
• User should be able to set the theme from the article tool bar and the Settings screen. Settings should be applied immediately (any visible UX should respond in real time to changes) and across the app (not on a per article basis).
• Allow the user to "dim" images, reducing ALL image brightness across the app.
• [Nice to have] Provide an affordance to dim the screen from same options for .
• [Nice to have] Provide a mechanism to enable and disable night mode "automatically" based on some environmental or context information.

Please see