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%;
}