(as suggested in bug 23315 comment 1)
In JavaScript gadgets can be used on any wiki and/or in any language since wgCanonicalSpecialPageName is available. However in CSS it's not quite as easy since there's only page-(wgPageName) which is (and should) be localized.
So that http://de.wikipedia.org/w/index.php?title=Spezial:Beiträge would have
<body class="mediawiki ltr ns--1 ns-special page-Spezial_Beiträge special-Contributions skin-vector">
instead of
<body class="mediawiki ltr ns--1 ns-special page-Spezial_Beiträge skin-vector">
Version: 1.18.x
Severity: normal