多个爱心层叠上下翻转波浪动画特效

引入js文件和css文件：

<script src="js/script.js"></script>
<link rel="stylesheet" href="css/style.css">

HTML代码：

<h1><span>❤</span><span>❤</span><span>❤</span><span>❤</span><span>❤</span><span>❤</span><span>❤</span><span>❤</span></h1>