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

header {
  background-color: #222;
  color: white;
  text-align: center;
  padding: 15px;
}

header:hover {
  background-color: red;
}

.content {
  display: flex;
  justify-content: space-around;
  padding: 20px;
}

.card {
  width: 30%;
  background-color: #eee;
  padding: 20px;
  text-align: center;
}

.card:hover {
  background-color: green;
}

@media (max-width: 768px) {
  .content {
    flex-direction: column;
    align-items: center;
  }

  .card {
    width: 80%;
    margin-bottom: 15px;
  }
}

/* Mobile View */
@media (max-width: 480px) {
  header h1 {
    font-size: 20px;
  }
}