img {max-width:100%;}

body {
  margin-left: auto;
  margin-right: auto;
  width:90%;
  max-width: 40rem;
}

html { font-size: 12pt; }

@media (min-width: 640px) {
    html { font-size: 16pt; }

    .two-columns-example {
        display: flex;
    }

    .two-columns-example > * {
        width: 50%;
    }

  }