body {
  margin: 0;
  font-family: Arial, sans-serif;
}

header {
  background: #003366;
  color: white;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: bold;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 1rem;
  padding: 0;
}

nav a {
  color: white;
  text-decoration: none;
}

.ad-top, .ad-bottom {
  width: 100%;
  height: 100px;
  background: #ccc;
  margin: 1rem 0;
}

.features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  padding: 2rem;
}

.products {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  padding: 2rem;
}

@media (max-width: 768px) {
  .features,
  .products {
    grid-template-columns: 1fr;
  }

  .ad-top, .ad-bottom {
    height: 60px;
  }
}

.card, .product {
  border: 1px solid #ccc;
  padding: 1rem;
  text-align: center;
}