OOUI has a nice demo at https://doc.wikimedia.org/oojs-ui/master/demos/?page=widgets&theme=wikimediaui&direction=ltr&platform=desktop. Got a demo for Codex yet? If so, maybe link it in the article. Trying to get an idea of whether or not Codex is visually different from OOUI. Thanks.
Topic on Talk:Codex
The documentation linked to in the first paragraph also contains examples (work in progress, but plenty to have a look at).