Manual:User group CSS and JavaScript

User group CSS and JavaScript is possible since MediaWiki 1.18 (specifically r82285). This means that CSS and JavaScript can be loaded per user group. CSS and JavaScript pages take the form where X is the user group name.
 * and

The special group "*" doesn't load the specific MediaWiki:Group-*.css or .js page; the special group "user" only loads its MediaWiki:Group-user.css and .js pages since MediaWiki 1.23. See ResourceLoaderUserGroupsModule.php for reference.

Examples:
 * MediaWiki:Group-sysop.css and MediaWiki:Group-sysop.js (code for sysops/administrators)
 * MediaWiki:Group-autoconfirmed.css and MediaWiki:Group-autoconfirmed.js (code for autoconfirmed users)
 * MediaWiki:Group-bureaucrat.css and MediaWiki:Group-bureaucrat.js (code for bureaucrats)