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%; }
}