untitled

<!doctype html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title>My Playground</title>
        <link rel="stylesheet" href="styles.css" />
    </head>
    <body>
        <h1 id="greeting">Hello, world!</h1>
        <button id="btn">Click me</button>
        <script src="script.js"></script>
    </body>
</html>