header {
  margin-bottom: 20px;
}

header #logo {
  display: block;
  width: 50%;
  margin: 40px auto;
}

header > nav > a {
  display: inline-block;
  margin: 0 50px;
  font-family: 'Trebuchet MS', sans-serif;
  font-size: 55px;
  font-weight: bold;
  color: black;
  cursor: pointer;
}

header > nav > a.active {
  border-bottom: 10px solid black;
  padding-bottom: 10px;
}