<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<title> css3圆形轨迹动画 </title>
<style type="text/css">
@keyframes animX{
0% {left: 0px;}
100% {left: 500px;}
}
@keyframes animY{
0% {top: 0px;}
100% {top: 500px;}
}
#ball {
width: 20px;
height: 20px;
background-color: #f66;
border-radius: 50%;
position: absolute;
animation: animX 4s cubic-bezier(0.36,0,0.64,1) -2s infinite alternate, animY 4s cubic-bezier(0.36,0,0.64,1) 0s infinite alternate;
}
#lopp {
width: 498px;
height: 498px;
border: 2px solid #999;
border-radius: 50%;
position: absolute;
left: 9px;
top: 9px;
}
</style>
</head>
<body>
<div id="lopp"></div>
<div id="ball"></div>
</body>
</html>
来源：https://www.cnblogs.com/Gavinzhong/p/6909237.html