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; }
}



@media (min-width: 640px) {
  .two-columns-example {
    display: flex;
  }
  .two-columns-example > *{
    width: 50%
  }
}