.header {
  background-color: #333;
  color: white;
  padding: 20px;
}

#navigation {
  display: flex;
  justify-content: space-between;
}

.nav-item {
  margin: 0 10px;
  color: #666;
}

@media (max-width: 768px) {
  .responsive-container {
    flex-direction: column;
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.animated {
  animation: fadeIn 1s ease-in-out;
}