test/index.html

<!doctype html>
<html>
    <head>
        <title>GitHub Web Widget</title>
        <link
            rel="stylesheet"
            href="https://unpkg.com/bootstrap@5.3.2/dist/css/bootstrap.min.css"
        />
        <link
            rel="stylesheet"
            href="https://unpkg.com/github-markdown-css@5.5.0/github-markdown.css"
        />
        <link
            rel="stylesheet"
            href="https://unpkg.com/prismjs@1.29.0/themes/prism-okaidia.css"
        />
        <script src="https://polyfill.web-cell.dev/feature/ECMAScript.js"></script>
        <script src="https://polyfill.web-cell.dev/feature/WebComponents.js"></script>
        <script src="https://polyfill.web-cell.dev/feature/ElementInternals.js"></script>
        <script src="https://polyfill.web-cell.dev/feature/Detail.js"></script>
    </head>
    <body>
        <script type="module" src="index.tsx"></script>
    </body>
</html>