效果图：小球沿着圆圈进行转动，利用css3的animation特性
代码如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style type="text/css">
*{
margin: 0;
padding: 0;
}
html,body{
height: 100%;
background-color: red;
}
#box{
width: 200px;
height: 200px;
margin: 200px auto;
border-radius: 50%;
border:2px solid white;
position: relative;
animation: run 3s ease infinite;
}
#box::before{
content: "";
display: block;
width: 20px;
height: 20px;
border-radius: 50%;
position: absolute;
background-color: white;
left: 90px;
margin-top: -10px;
}
@keyframes run{
from{
transform: rotate(0deg);
}
to{
transform: rotate(360deg);
}
}
</style>
</head>
<body style="position: relative;">
<div id="box"></div>
</body>
</html>