body {
   background-color: #f9f9f9;
}

main {
  margin: 0;
}

.article {
  font-family: Arial, Helvetica, sans-serif;
}

.header {
  margin: 2.5em auto;
  text-align: center;
}

.header>h1 {
  margin-bottom: 0;
  font-weight: 400;
  font-size: 2.2em;
}

.header>p {
  margin-top: 0;
  font-size: 1.2em;
}

footer {
  margin: 2em 0 0;
  text-align: center;
  font-size: 14px;
}

footer>span {
  margin: 16px;
}

@media (min-width: 640px) {
  main {
    margin: 0 96px;
  }
}