input.achievement-openbadges-backpack-button {
  background-color: transparent;
  background-image: url('images/backpack.png');
  background-position: 0 2px;
  background-repeat: no-repeat;
  border: none;
  cursor: pointer;
  height: 22px;
  margin-left: -41px;
  margin-top: -4px;
  opacity: .5;
  width: 41px;
}
input.achievement-openbadges-backpack-button:hover {
  opacity: 1;
}