body {
  font-family: Arial, sans-serif;
  background-color: #f2f2f2;
}

header {
  background-color: #333;
  color: #fff;
  padding: 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

nav {
  background-color: #333;
  position: fixed;
  top: 0;
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1;
}

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

nav li {
  margin-right: 20px;
}

nav li a {
  display: block;
  color: #fff;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  border-bottom: 2px solid transparent;
}

nav li a:hover {
  background-color: #ddd;
  border-bottom: 2px solid #fff;
}

section {
  background-color: #fff;
  padding: 20px;
  margin: 20px;
}

footer {
  background-color: #333;
  color: #fff;
  padding: 20px;
  text-align: center;
}