<!DOCTYPE html>

<html>
<head>
    <style>
        .wrapper {
            overflow: hidden;
            height: 200px;
            width: 200px;
            margin: 50px;
            border: 1px solid black;
        }

        .filtered {
            width: 100%;
            height: 100%;
            background-color: black;
            filter: blur(10px);
        }
    </style>
</head>
<body>
    <div class="wrapper">
        <div class="filtered">
        </div>
    </div>
</body>
</html>