a.best-answer-select-answer  {
  display: block;
  width: 60px;
  height: 60px;
  text-indent:-9999px;
  float: left;
  background: url(graphics/select_button.png) no-repeat;
}

a.best-answer-select-answer:hover{
  background-position: 0 -60px;
}

a.best-answer-this-answer {
  width: 60px;
  height: 60px;
  float: left;
  background: url(graphics/select_button.png) no-repeat;
  background-position: 0 -60px;
  border: 0;
 }