body {
  margin: 28px auto;
  max-width: 300px;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
  line-height: 1.25;
  color: #111;
  background: #fff;
}

a {
  color: #0000ee;
}

img {
  max-width: 100%;
  height: auto;
}

.mono {
  font-family: "Courier New", Courier, monospace;
}

.small {
  font-size: 12px;
}

.big-spacer {
  height: 30px;
}

.rule {
  border: 0;
  border-top: 1px solid #111;
  margin: 26px 0;
}

@media (max-width: 600px) {
  body {
    margin: 16px;
  }

  .spacer {
    height: 55px;
  }

  .big-spacer {
    height: 100px;
  }
}