body {
  font-family: Arial, sans-serif;
  line-height: 1.6;
  margin: 0;
  padding: 0;
  background-color: #f4f4f4;
  color: #333;
}

header {
  background: #333;
  color: #fff;
  padding: 1rem 0;
  text-align: center;
}

nav ul {
  background: #444;
  color: #fff;
  list-style: none;
  padding: 0;
  text-align: center;
}

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

nav ul li a {
  color: #fff;
  padding: 0.5rem 1rem;
  text-decoration: none;
}

main {
  padding: 1rem;
}

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

figure,
pre {
  display: block;
  margin-left: auto;
  margin-right: auto;
  text-align: center;
  max-width: 90%;
}

figure img {
  max-width: 100%;
  height: auto;
}

figcaption {
  margin-top: 0.5rem;
  font-style: italic;
}

pre {
  background-color: #cfcfcf;
  padding: 1rem;
  border-radius: 4px;
  overflow-x: auto;
  text-align: left;
}