.tuna {
  animation: 
    walk-cycle 1s steps(12) 2,
    walk-to-run .75s steps(12) 2s 1, 
    run-cycle .75s steps(13) 2.75s infinite;
  background: url(../images/animation/cat_sprite.png) 0 0 no-repeat; 
  height: 200px;
  width: 400px;
  position: absolute;
  bottom: 1px;
  left: 100%;
  right: 0%;
  margin : auto;
  translate3d(0,0,0);
}

@keyframes walk-cycle {  
  0% {background-position: 0 0; } 
  100% {background-position: 0 -2391px; } 
}

@keyframes walk-to-run {  
  0% {background-position: -400px 0; } 
  100% {background-position: -400px -2391px; } 
}

@keyframes run-cycle {  
  0% {background-position: -800px 0; }
  100% {background-position: -800px -2591px; } 
}