Mobile design/System messages

This document describes some ideas for a consistent set of system messages on mobile Wikipedia.

Rationale
Messages that provide guidance, instruction, and feedback are important for making users feel comfortable with the mobile interface, and they should be styled consistently, so that they don't confuse and distract readers. Since some features will look and behave differently on mobile than they do on desktop Wikipedia, notices and instructional messages are important even for experienced editors who generally know how the features work.

Goals

 * Create messages that are minimally distracting but capture a user's attention enough to deliver the salient information
 * Style messages consistently if possible, but don't break with intelligible UI patterns
 * Use the appropriate colors, where necessary

Potential use-cases

 * Watchlist: a message to alert the user that an article has been added to or removed from their watchlist


 * e.g., Added "Foo" to your watchlist
 * e.g., Removed "Foo" from your watchlist


 * Editing: a message to alert the user of the state of their edit


 * e.g., Your edit has been saved
 * e.g., Leave this page? Your edit won't be saved