As discussed in

• T91201: [GOAL] Accessibility settings/preferences on desktop and mobile
• T72879: Simple accessibility preferences
• T50946: Add font size adjustment feature
• T26739: Ability to dynamically change base font-size of Mediawiki

Anything accessibility & usability, that is purely reading-related could be moved to a simple site-style menu, and thereby become available to logged-out users, too.

The skin-system is in the process of being overhauled, and hopefully more modular possibilities will arise from that. We should aim to: Provide sensible defaults, but make the fundamental settings easy to tweak. So that people who want (less clutter vs more metadata everywhere) or (basic design vs more complex-tools vs more styled design) or (etc...) can choose for themselves.

(Sidenote: The GPII.net (Global Public Inclusive Infrastructure) and connected projects seems to be aiming at this, at a global scale; see FLOE project and click "show preferences" in the top-right of the window).

I included "Appearance" as well as "Accessibility", partially because they ''often'' overlap, and partially because FLOE and GPII do the same. I included line-spacing (formerly labelled "density") because it's the most prominent option in gmail; and because FLOE included it; and because it's a frequently discussed/divisive aspect of Flow. I also tried to include many of the visual elements that don't have subjective "right" answers, and that opinion is split on - but some more elements could/should be added such as "collapsible sidebar" for the left-hand (for LTR) site sidebar, which has been heavily discussed but noone can agree to change the default.

Relevant examples:

• Wikiwand's settings flyout - (screenshot1 - screenshot2)
• NYTimes 3-level font-size options - (screenshot)
• GMail's 3-level interface-density options - (screenshot, details)
• Southampton University accessibility panel - (screenshot, live)
• Battlefield's 3 color-blind options - (4 screenshots)
• Fixed-width experiments in Typography Refresh and Flow - Some users love this (eg); Some like the idea but want to be able to change the default width; Some want (the current) full-width. We should make it changeable. One possibility is to make it "resizable", just like the editing-text-box currently is (which also has a hard-override in Preferences->editing for columns and rows). Maybe http://jqueryui.com/resizable/#snap-to-grid or similar?
• Reference Tooltips has, and Hovercards will have, an opt-out for anons. Reference Tooltips has 2 additional settings (timing-delay, and hover/click to activate - screenshot)