<div class="scrolling-limit">
  <div class="scrolling">
    I am scrolling!I am scrolling!I am scrolling!
    I am scrolling!I am scrolling!I am scrolling!
    I am scrolling!I am scrolling!I am scrolling!
  </div>
</div>

div.scrolling-limit{
  width: 300px;
  height: 20px;
  background-color: yellow;
  overflow:hidden;
  white-space:nowrap;
  
}

div.scrolling{
  position: relative;
  -webkit-animation: scroll 20s infinite linear;;
  -moz-animation: scroll 20s infinite linear;
  -o-animation: scroll 20s infinite linear;
  animation: scroll 20s infinite linear;
}

@keyframes scroll{
    0%   {left: 500px;}
    100% {left: -950px;}
}
@-webkit-keyframes scroll{
    0%   {left: 500px;}
    100% {left: -950px;}
}