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%;
  }
}