<!DOCTYPE html>

<html>
<head>
    <style>
        .box {
            position: absolute;
            top: 50px;
            left: 50px;
            height: 100px;
            width: 100px;
            background-color: blue;
            box-shadow: 0 0 20px black;
        }
        
        .child {
            position: absolute;
            top: 0px;
            left: 0px;
            width: 100px;
            height: 100px;
            background-color: silver;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="child"></div>
    </div>
</body>
</html>