Because some like it like that:

    @namespace url(http://www.w3.org/1999/xhtml);
    @-moz-document regexp("*.stackexchange.com|superuser.com|askubuntu.com|serverfault.com|mathoverflow.com|stackapps.com|stackoverflow.com")
    {
      #question-header, 
     .summary h3 a,
      #hot-network-questions li 
      {text-transform: capitalize !important;}
    }