@media (max-width: 767px) {
  /* Header */
  header {
    flex-direction: column;
    text-align: center;
    padding: 10px;
  }

  nav ul {
    flex-direction: column;
    align-items: center;
  }

  nav ul li {
    margin: 10px 0;
  }

  /* Dropdown Menu */
  .dropdown {
    position: static;
    display: block;
    width: 100%;
    box-shadow: none;
  }

  .dropdown-column {
    width: 100%;
    padding: 10px 0;
  }

  /* Banner */
  .banner {
    padding: 20px 15px;
  }

  .banner h1 {
    font-size: 22px;
  }

  .banner p {
    font-size: 14px;
  }

  .banner .btn {
    font-size: 14px;
    padding: 8px 12px;
  }

  /* Product Cards */
  .product-grid {
    flex-wrap: wrap;
    flex-direction: column;
    align-items: center;
  }

  .product-card {
    width: 90%;
    margin-bottom: 20px;
  }

  /* Checkout Form */
  .checkout-form {
    padding: 15px;
    width: 100%;
  }

  .checkout-form .form-group input,
  .checkout-form .form-group textarea {
    font-size: 14px;
  }

  /* Buttons */
  .btn {
    font-size: 14px;
    padding: 8px 12px;
  }
}