Как сделать такой переключатель картинки

<!-- Кнопка регистрации -->
                     <style>
                     .btn_rec {
                          background-image: url("/templates/BobFilm/images/btn_rec.jpg");
                          background-repeat: no-repeat;
                          background-position: 0 0;
                          display: block;
                          height: 75px;
                          width: 222px;
              margin: 10px 0 0 -7px;
                     }
                     .btn_rec:hover {
                          background-position: -222px 0;
                     }
                     </style>
                     <a href="/index.php?do=register" class="btn_rec"></a>
                     <!-- Кнопка регистрации -->