Gadget export
To export the mobile-sidebar gadget, click on "Download" button, save the downloaded file, go to Special:Import on the destination wiki and upload it. Then add the following to MediaWiki:Gadgets-definition page:
* mobile-sidebar[ResourceLoader|type=general]|mobile-sidebar.js|mobile-sidebar.css
You must have appropriate permissions on the destination wiki (including the right to edit system messages) and import from file uploads must be enabled.