Skins allow users to customize the look and feel of MediaWiki.
Basic knowledge of CSS and PHP is helpful.
Check the project page in Phabricator for more information on each skin and contact information.
Messages displayed in the user interface often need small corrections to the English text. The source text can only be changed in the code by developers, contrary to translations.
Also, many messages are unclear and require better documentation.
Missing documentation can also be added by editing the /qqq subpage of the message on translatewiki.net, like all translations, but may require some study of the code to understand what a message is for.