<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
#box{
position: relative;
}
span{
position: absolute;
width: 30px;
height: 30px;
background: white;
border-radius: 50%;
}
span:nth-child(1){
-webkit-animation: a 1.5s infinite linear;
}
span:nth-child(2){
-webkit-animation: b 1.5s infinite linear;
}
@-webkit-keyframes a{
0%{-webkit-transform: translateX(0px); opacity: 1;}
50%{-webkit-transform: translateX(80px); opacity: 0.5;}
100%{-webkit-transform: translateX(0px); opacity: 1;}
}
@-webkit-keyframes b{
0%{-webkit-transform: translateX(80px); opacity: 1;}
50%{-webkit-transform: translateX(0px); opacity: 0.5;}
100%{-webkit-transform: translateX(80px); opacity: 1;}
}
</style>
</head>
<body style="background-color: darkcyan;">
<div id="box">
<span></span>
<span></span>
</div>
</body>
原文：http://www.cnblogs.com/luckyXcc/p/5721136.html