Board Thread:Support Requests - Designing Your Wikia/@comment-5293793-20140526034039/@comment-4018164-20140526065334

They use ShowHide. You'd need to import it as well for them to work, however, ShowHide is marked as "no longer in use" as wikia now has built-in features for collapsing, which can be added by giving the navbox table a class of mw-collapsible. Try perhaps, to make it read the same show-hide text: {| class="mw-collapsible mw-collapsed" data-expandtext="Show" data-collapsetext="Hide" And in addition, some CSS can be used to change the styling of the "show" and "hide".

If you're having some problems applying it, please link to the navbox template in your wiki.