Board Thread:Support Requests - Getting Technical/@comment-25050081-20160507172447/@comment-1757994-20160507182024

The navboxes on the Casualty wiki appear to be using custom classes and custom JavaScript for collapsing.

Although that doesn't preclude getting any help here, it does make it less likely.

FYI: The MediaWiki-supplied classes are  and. There are others for people who want more customization, but the JavaScript to use them is all included with MediaWiki.