index.html

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Checkout Frames v2: 1-liner</title>
  <link rel="stylesheet" href="style.css">
</head>

<body>

  <form id="payment-form" method="POST" action="server/server.php">
    <div class="one-liner">
      <div>
        <input type="text" name="" placeholder="FirstName">
        <input type="text" name="" placeholder="LastName">
      </div>
      <div class="card-frame"></div>
      <button id="pay-button" disabled>
        PAY GBP 24.99
      </button>
    </div>
    <p class="error-message"></p>
    <p class="success-payment-message"></p>
  </form>

  <script src="https://cdn.checkout.com/js/framesv2.min.js"></script>
  <script src="app.js"></script>

</body>

</html>