popup.html

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

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="popup.css">
</head>

<body>
    <h1>URL Shorter</h1>
    <input type="text" id="shortUrl"><br>
    <canvas id="qr-canvas" width="200" height="200"></canvas>
    <script src="./popup.js" type="module"></script>
</body>

</html>