css3 loading 效果3

代码：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
#box{position: relative;margin: 100px;}
#box span{
    display: block;
    width: 20px;
    height: 20px;
    position: absolute;
    background-color: #3498db;
    opacity: 0.5;
    border-radius: 50%;
    -webkit-animation:preloader 1s infinite ease-in-out;
}
#box span:nth-child(2){left: 20px;-webkit-animation-delay:0.2s;}
#box span:nth-child(3){left: 40px;-webkit-animation-delay:0.4s;}
#box span:nth-child(4){left: 60px;-webkit-animation-delay:0.6s;}
#box span:nth-child(5){left: 80px;-webkit-animation-delay:0.8s;}
@-webkit-keyframes preloader{
    0%{opacity: 0.3;-webkit-transform:translateY(0px);box-shadow: 0px 0px 3px rgba(0,0,0,0.1);}
    50%{opacity: 1;-webkit-transform:translateY(-10px);box-shadow: 0px 20px 3px rgba(0,0,0,0.05);background-color: #f1c40f;}
    100%{opacity: 0.3;-webkit-transform:translateY(0px);box-shadow: 0px 0px 3px rgba(0,0,0,0.1);}
}
</style>
</head>
<body>
    <div id="box">
        <span></span>
        <span></span>
        <span></span>
        <span></span>
        <span></span>
    </div>
</body>
</html>
效果图：
高否？富否？帅否？否？滚去学习！