index.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="index.css">
    <title>Repos</title>
</head>
<body>
    <nav id="navbar">
      <a href="" class="nav-brand">App</a>
      <ul>
        <li class="nav-item"><a href="about.html">About us</a></li>
        <li><a href="" class="nav-item btn btn-default">Register</a></li>
      </ul>
    </nav>

    <div class="container" id="main">
        <h1>GitHub repos</h1>
         <form id="repos-form">
            <label for="github-username">GitHub username</label>
            <input id="github-username" type="text" placeholder="GitHub username">
            <button type="submit" id="get-repos" class="btn btn-default">Get repos</button>
        </form>
        <ul id="repos-list"></ul>
    </div>

    <footer id="footer-wrapper">
        <a href="about.html" target="_blank">About us</a>
        <a href="contact.html" target="_blank">Contact us</a>
    </footer>
    <script src="./index.js" type="module"></script>
</body>
</html>