Wiki: https://arboretumfictoria.miraheze.org
Common.js has a script that detects if a page has element of the form <div class="inject-body-class">(string)</div> then adds (string) to the body class list.
This does not happen; an error "scripts need to be valid ECMAScript 5" is thrown, despite MW 1.41 supporting ECMAScript 6. (ECMAScript 6 introduces the let keyword, which Common.js uses)