materio-base-d7/sites/all/modules/contrib/theming/extlink/extlink.css

span.ext {
  background: url(extlink_s.png) 2px center no-repeat;
  width: 10px;
  height: 10px;
  padding-right: 12px;
  text-decoration: none;
}
span.mailto {
  background: url(extlink_s.png) -20px center no-repeat;
  width: 10px;
  height: 10px;
  padding-right: 12px;
  text-decoration: none;
}

/* Hide the extra spans when printing. */
@media print {
  span.ext,
  span.mailto {
    display: none;
    padding: 0;
  }
}