定格动画CSS

我正在创建一个正在运行的猫的定格动画.我已准备好所有幻灯片.但它似乎没有正常工作:

div {
  animation: run 1s steps(10) infinite;
  -webkit-animation: run 1s steps(10) infinite;
  background: url(http://stash.rachelnabors.com/img/codepen/tuna_sprite.png) 0 0; 
  background-repeat: no-repeat;
  height: 200px;
  width: 400px;
}

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

div {
  animation: run 1s steps(13) infinite;
  -webkit-animation: run 1s steps(13) infinite;
  background: url(http://stash.rachelnabors.com/img/codepen/tuna_sprite.png) 0 0; 
  background-repeat: no-repeat;
  height: 200px;
  width: 400px;
}

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