Each lemma on Wikipedia has a list of other languages with that lemma. That list is great as a dictionary, and to get more information on a subject, but it can get big. Too big. Here’s a little trick to make it more manageable.

The Firefox extension Stylish allows you to install your own CSS style sheets for some sites. You can create your own style sheet to mark some languages. Here’s mine:

@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document domain("wikipedia.org") {
  li.interwiki-en, li.interwiki-nl, li.interwiki-simple {
    font-weight: bold;
    margin-left: -13px !important;

  li.interwiki-en:before, li.interwiki-nl:before,
      li.interwiki-simple:before {
    content:"⚫ ";

Simple English highlighted in the Wikipedia languages listThis highlights English (“en”), Dutch (“nl”) and Simple English (“simple”) in the Wikipedia sidebar by making them bold and putting a big dot in front. Other languages will not change.

If you want to mark different languages, simply change interwiki-nl to a different language code. You can add more languages or remove some by using the Alpha2 country codes.

Wikipedia’s page on Wikipedia is a great place to test your setup.

Update 17 March 2015: the example script is available on GitHub.