Figure out the art direction/guidelines

Let's get the conversation started on the art direction. The keywords are simplicity and clarity: the art shouldn't take too long to create, update or extend. And it should be consistent.

We got started this morning with @guilhermehto, as he's working on UI tutorials :


Start by reviewing the example image and the UI-tutorial context mentioned in the issue. Done means the project has agreed art-direction guidelines covering simplicity, clarity, consistency, and ease of updating or extending; the issue names no files or tests to run.

Written by the indexing model from the issue text.