Jumpy white arrow pointing down

animated-arrow-down.css

.arrow-down {
  display: block;
  margin: 25px auto 0;
  width: 0; 
  height: 0; 
  position: relative;
  border-left: 10px solid transparent;
  border-right: 10px solid transparent;  
  border-top: 15px solid #fff;
  -webkit-animation: arrowDown 2s infinite;
     -moz-animation: arrowDown 2s infinite;
          animation: arrowDown 2s infinite;
}

@keyframes arrowDown {
  0% {
    top: 0;
  }
  25% {
    top: 10px;
  }
  50% {
    top: 0px;
  }
}
@-webkit-keyframes arrowDown {
  0% {
    top: 0;
  }
  25% {
    top: 10px;
  }
  50% {
    top: 0px;
  }
}
@-moz-keyframes arrowDown {
  0% {
    top: 0;
  }
  25% {
    top: 10px;
  }
  50% {
    top: 0px;
  }
}