hr.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Hex Random</title>
    <style>
        body {
            font-family: monospace;
            word-break: break-all;
        }
    </style>
</head>

<body>
    <script>
        setInterval(function () {
            document.body.innerHTML += (
                (Math.random() * 16) | 0
            ).toString(16);
        }, 10);
    </script>
</body>

</html>