index.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">
    <title>BG Color Switch</title>
    <link rel="stylesheet" href="css/style.css">
</head>
<body>

    <div class="main">
        <div class="box">
           <input type="text" id="input" placeholder="Type color....."><br /><br />
        </div>
     <a href="#" id="button" type="submit" autocomplete='off'>Click Me</a>
    <div id="copy">Click to copy color</div>
    </div>

    <script src="./app.js"></script>
</body>
</html>