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%}
  }