body {
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f9f9f9;
  color: #333;
}

nav {
  background-color: #ffffff;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  position: sticky;
  top: 0;
  z-index: 1000;
  text-align: center;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 10px 0;
  display: inline-flex;
  gap: 30px;
}

nav ul li a {
  text-decoration: none;
  color: #333;
  font-weight: 500;
  font-size: 1.05em;
  transition: color 0.3s ease;
}

nav ul li a:hover {
  color: #0073e6;
}

header {
  background-color: #0073e6;
  color: white;
  padding: 40px 20px;
  text-align: center;
  border-bottom: 5px solid #005bb5;
}

header h1 {
  margin: 0;
  font-size: 2.5em;
}

main {
  max-width: 800px;
  margin: 40px auto;
  background-color: white;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

main p {
  font-size: 1.1em;
  margin: 15px 0;
  line-height: 1.6;
}

main strong {
  color: #0073e6;
}

footer {
  text-align: center;
  padding: 20px;
  font-size: 0.9em;
  background-color: #f0f0f0;
  margin-top: 40px;
}

@media (max-width: 600px) {
  nav ul {
    flex-direction: column;
    gap: 10px;
  }

  main {
    margin: 20px;
    padding: 20px;
  }

  header h1 {
    font-size: 2em;
  }
}