User blog comment:DaNASCAT/Technical Update: September 25, 2017/@comment-168424-20170925213206/@comment-27345308-20170926084101

TK's translated answer means: "Tabber has CSS and JS that goes with it but it's only loaded when the parser sees a tabber used on a page. Since your template transcluded from Community Central is just transferred as HTML and not actually parsed the page doesn't know there's a tabber on it and doesn't load CSS and JS that goes with tabbers." Before the change, I'm pretty sure tabber CSS and JS was loaded on all pages.

To fix this, you have to use a tabber tag on the page to force loading of tabber CSS and JS on it. Here's an example.