img {
  max-width: 100%;
  height: auto;
}
.two-columns-example {
  margin: 1em 0;
}
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%;
  }
  }
}