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%;}
  }