Last modified: 2014-10-04 00:52:02 UTC
Gadgets and Mediawiki:Common.css and .js do not work in 'Special:Login' and 'Special:Preferences' pages.
MediaWiki:Common.js and Gadgets have never worked on those special pages. CSS was recently removed with bug 70672. See also bug 71621 which wants to re-allow CSS on those pages. So, WONTFIX because this is intentional.