<head>
    <title></title>
    <style>
        .pai {
            width: 100px;
            height: 175px;
            border: 1px solid black;
            border-radius: 20px;
            background-color: white;
            box-shadow: 5px 5px 10px gray;
            position: absolute;
            transition: all 1s;
        }
    </style>
</head>

<body style="overflow: hidden;">
</body>
<script>
    var arr = [];
    for (var i = 0; i < 15; i++) {
        var div = document.createElement("div");
        div.classList.add("pai");
        arr.push(div);
        document.body.appendChild(div);
    }
    setInterval(function() {
        var left = Math.random() * (window.innerWidth - 400);
        var top = Math.random() * (window.innerHeight - 400);
        var step = 20;
        for (var y = 0; y < arr.length; y++) {
            arr[y].style.left = (left - step * y) + "px"
            arr[y].style.top = (top - step * y) + "px"
            arr[y].style.transitionDelay = (y * 0.05) + "s"
            arr[y].style.zIndex = 20 - y
        }
    }, 1000)
</script>