@namespace url(http://www.w3.org/1999/xhtml);

@-moz-document url-prefix(https://mail.google.com),
               url-prefix(http://mail.google.com)
{
  #ds_spam b {
      visibility: hidden;
  }

  #ds_drafts b {
      visibility: hidden;
  }
 
  #ds_spam b::before {
      content: "Spam";
      visibility: visible;
      font-weight: normal;
  }
 
 #ds_drafts b::before {
      content: "Drafts";
      visibility: visible;
      font-weight: normal;
  }
}