<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>CSS实现：一个矩形内容，有投影，有圆角，hover状态慢慢变透明</title>
    <style>
        body{margin:0;padding:0;}
        .m-test{width: 200px;height: 100px;border-radius: 10px;box-shadow: 10px 10px 5px #888888; background-color: green;transition: 0.7s; }
        .m-test:hover {opacity: 0;}  
    </style>
</head>
<body>
<div class="m-test">
</div>
 
</body>
</html>