index.html

<!DOCTYPE html>
<html lang="en-us">
    <head>
        <meta charset="utf-8">
        <meta name="description" content="simon game remember the color sequences">
        <meta name="author" content="JS developer">
        <title>simon_game</title>
        <meta name="viewport" content="width=device-width,initial-scale=1.0">
        <link rel="stylesheet" href="styles.css">
    </head>
    <body>
        <h1 id="level-title">Press any key to start</h1>
        <button id="start-button">Start</button>
        <div class="container">
            <div class="row">
                <div id="green" class="btn green">

                </div>
                <div id="red" class="btn red">

                </div>
            </div>
            <div class="row">
                <div id="yellow" class="btn yellow">

                </div>
                <div id="blue" class="btn blue">
                    
                </div>
            </div>
        </div>
        <script src="index.js"></script>
    </body>
</html>