css3背景图片无间断滚动

类名{

background: url(../images/bg.png) 0 bottom repeat-x;

    -webkit-animation: animate-cloud 20s linearinfinite;
    -moz-animation: animate-cloud 20s linear infinite;
    -ms-animation: animate-cloud 20s linear infinite;

    -o-animation: animate-cloud 20s linear infinite;

    animation: animate-cloud 20s linear infinite;

}

动画

@-webkit-keyframes animate-cloud {
  from {
    background-position: 600px 100%;
  }
  to {
    background-position: 0 100%;
  }
}
@-moz-keyframes animate-cloud {
  from {
    background-position: 600px 100%;
  }
  to {
    background-position: 0 100%;
  }
}
@-ms-keyframes animate-cloud {
  from {
    background-position: 600px 100%;
  }
  to {
    background-position: 0 100%;
  }
}
@-o-keyframes animate-cloud {
  from {
    background-position: 600px 100%;
  }
  to {
    background-position: 0 100%;
  }
}