header {
  font-family: Arial, Helvetica, sans-serif;
  background-color: #eee;
  border-bottom: 1px solid #ccc;
}

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

header nav ul li {
  display: inline;
}

header nav ul li * {
  padding: 1rem;
}

header nav ul li:hover {
  background-color: #ccc;
}

header nav ul li a,
header nav ul li a:hover,
header nav ul li a:visited {
  display: block;
  text-decoration: none;
  font-weight: bold;
  color: black;
}

.active {
  background-color: #ccc;
}