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

header {
  background-color: #4CAF50;
  padding: 10px 0;
  text-align: center;
}

nav ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
}

nav ul li {
  display: inline;
  margin: 0 15px;
}

nav ul li a {
  color: white;
  text-decoration: none;
  font-size: 18px;
}

section {
  padding: 20px;
  text-align: center;
}

footer {
  background-color: #333;
  color: white;
  text-align: center;
  padding: 10px 0;
  position: relative;
  width: 100%;
  bottom: 0;
}

@media (max-width: 600px) {
  nav ul li {
    display: block;
    margin: 10px 0;
  }
}