CSS3过渡效果

家乡区县：都江堰市

<!doctype html>
<html>
<head>
<style>
#aa{
position:absolute;
width:50px;
height:50px;
border-radius:50px;
background-color:red;
-webkit-animation:myfirst 3s alternate infinite;
}
@-webkit-keyframes myfirst
{
0%{background:red;top:0px;left:0px;}
25% {background:yellow;top:200px;left:50px;}
50%{background:lightblue;top:0px;left:100px;}
75% {background:lightgreen;top:200px;left:150px;}
100%{background:black;top:0px;left:200px;}
}