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

header, footer {
  background-color: #333;
  color: white;
  padding: 1rem;
  text-align: center;
}

nav {
  background-color: #555;
}

nav ul {
  display: flex;
  list-style-type: none;
  margin: 0;
  padding: 0;
  justify-content: center;
}

nav li {
  margin: 0;
}

nav a {
  display: block;
  padding: 1rem;
  color: white;
  text-decoration: none;
}

nav .active a,
nav a:hover {
  background-color: #222;
}

aside {
  padding: 1rem;
  background-color: #f0f0f0;
}

.content {
  padding: 1rem;
}

footer {
  margin-top: 2rem;
}