body {
  font-size: 18px;
  padding: 0 4em;
  margin-left: 16em;
}

body > article, body > footer {
  margin: 0 auto;
  padding: 2em 0;
  max-width: 55em;
}

body > header {
  display: block;
  position: fixed;
  background: #17181c;
  color: #fff;
  border: none;
  box-shadow: none;
  opacity: .96;
  margin: 0;
  padding: 2.2em 2em;
  width: 12em;
  top: 0;
  bottom: 0;
  left: 0;
}

nav {
  margin: 0 -2em;
}

nav a {
  display: block;
  margin: 0;
  padding: .5em 2em;
}

nav a:hover, nav a.selected {
  background: #23242a;
  text-decoration: inherit;
}

nav a svg {
  margin-right: 1.2em;
}

article header h1 {
  font-size: 2em;
}

body > header > a {
  display: none;
}

body > header > p {
  margin-top: 3em;
}