html {
  box-sizing: border-box;
  font: 16px/1.5 "Helvetica Neue", Helvetica, Arial, sans-serif;
}

*, *::before, *::after {
  box-sizing: inherit;
}

body {
  margin: 0 auto;
  padding: 2rem;
  max-width: 40rem;
}

header {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
}

header h1 {
  margin: 0;
}

header p {
  margin: 0 0 0 1rem;
}

nav ul {
  padding: 0;
  list-style: none;
}

pre {
  padding: 1rem;
  font: 15px Consolas, monospace;
  background: #eee;
}

a:link {
  text-decoration: none;
}

a:focus, a:hover, a:active {
  background: #fdd;
}

@media (min-width: 60rem) {
  body {
    max-width: 56rem; /* 15 + 1 + 40 */
    display: grid;
    grid-template-columns: 15rem auto;
    grid-gap: 1rem;
  }

  header {
    grid-column: 1 / 3;
    grid-row: 1;
  }

  nav {
    grid-column: 1;
    grid-row: 2;
  }

  main {
    grid-column: 2;
    grid-row: 2;
  }

  main h2:first-child {
    margin-top: .5rem;
  }
}