.box2_jj{  position: relative;  }    
.box2_jj:nth-child(1){  -webkit-animation:jump 1s linear 0s infinite alternate;  }  
.box2_jj:nth-child(2){  -webkit-animation:jump 1s linear 0.2s infinite alternate;  }  
@-webkit-keyframes jump  { 0%{  top:0px;  color:red;  }  
            50%{  top:-10px; color:green;  }  
            100%{  top:10px; color:blue;  }