css3 动画

@-webkit-keyframes myfirst{
  0%  {background: red}
  50% {background: blue}
  100%{background: orange}
}
@keyframes myfirst{
  0%  {background: red}
  50% {background: blue}
  100%{background: orange}
}

#myfirst{
  -webkit-animation-name: myfirst;
  -webkit-animation-duration: 5s;
  -webkit-animation-timing-function: linear;
  -webkit-animation-delay: 2s;
  -webkit-animation-iteration-count: infinite;
  -webkit-animation-play-state: running;
  animation-name: myfirst;
  animation-duration: 5s;
  animation-timing-function: linear;
  animation-delay: 2s;
  animation-iteration-count: infinite;
  animation-play-state: running;
}
#myfirst{
  width:100px;
  height:100px;
}