CSS로 공이 튀는 애니메이션 효과를 얻는 방법은 무엇입니까? 공이 튀는 애니메이션 구현 예

 @-webkit-keyframes travel {
    from {              }
    to   { left: 640px; }
  }
  @keyframes travel {
    from {              }
    to   { left: 640px; }
  }

 @-webkit-keyframes bounce {
    from, to  {
      bottom: 0;
      -webkit-animation-timing-function: ease-out;
    }
    50% {
      bottom: 220px;
      -webkit-animation-timing-function: ease-in;
    }
  }
  @keyframes bounce {
    from, to  {
      botttom: 0;
      animation-timing-function: ease-out;
    }
    50% {
      bottom: 220px;
      animation-timing-function: ease-in;
    }
  }

#stage {
    position: relative;
    margin: 1em auto;
    width: 660px;
    height: 240px;
    border: 2px solid #666;
    background: #cff;
  }

#traveler {
    position: absolute;
    width: 20px;
    height: 240px;
    -webkit-animation-name: travel;
    -webkit-animation-timing-function: linear;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-direction: alternate;
    -webkit-animation-duration: 4.8s;
    animation-name: travel;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
    animation-direction: alternate;
    animation-duration: 4.8s;
  }
  #bouncer {
    position: absolute;
    width: 20px;
    height: 20px;
    background: red;
    border-radius: 10px;
    -webkit-animation-name: bounce;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-duration: 4.2s;
    animation-name: bounce;
    animation-iteration-count: infinite;
    animation-duration: 4.2s;
  }

<div id="stage">
   <div id="traveler">
       <div id="bouncer"><!-- --></div>
   </div>
</div>