index.html

<!DOCTYPE HTML>
<html lang="en">
    <head>
        <title>Dark Mode</title>
        <!-- Necessary libraries and hyper-links for the website -->
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <!-- Bootstrap Library for responsiveness -->
        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/css/bootstrap.min.css">
        <!-- Icon for the dark mode -->
        <script src="https://kit.fontawesome.com/91e547386c.js" crossorigin= "anonymous"></script>
        <!-- CSS reference for styling -->
        <link rel="stylesheet" href="index.css">
    </head>
    <body>
        <div class="outer">
            <div class = "container">
            <!-- Dark Mode Icon -->
                <a>
                    <i id="dark-mode-btn" class="toggler far fa-moon"></i>
                </a>
                <h1>Dark Mode</h1>
                <br>
                <h3>Purely coded with HTML, CSS and JavaScript.</h3>
                <br>
                <h4>Used Bootstrap library for responsiveness.</h4>
            </div>
        </div>
        <!-- JavaScript Referencing -->
        <script src="index.js"></script>
    </body>
</html>