We need a simple UI for turning dark mode on and off.
===Design Goals and Requirements
- **Easy to access: **The tool should be close to hand on every page of the wikis. The use case for this is that we believe dark mode will be something users turn on and off frequently. This is likely to be especially true of editors, who use lots of pages and UIs we don't plan to optimize for dark mode.
- **Available to all users,** logged in and logged out.
- **Name = 'Dark mode"**, not "Night mode," as we originally envisioned. This is more standard, including in our own iOS app.
Note: The ticket T218800 entertains ideas of combining Dark mode with other reading-preference features in a menu. Such developments will have to wait for future projects. The desire here is to have a very simple switch or toggle.