@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document domain("search.live.com") {
  /* Tested with german SERPs */

  ul[class="sb_results"] {
    counter-reset: pageNum;
  }

  ul h3:before {
    content: counter(pageNum) ": ";
    counter-increment: pageNum;
    font-weight: bold;
  }
}