article img {
  float: left;
  width: auto;
  max-width: 40%;
  height: auto;
  margin: 0 1rem 1rem 0;
  box-sizing: border-box;
}

article::after {
  content: "";
  display: block;
  clear: both;
}

@media (max-width: 640px) {
  article img {
    float: none;
    display: block;
    max-width: 100%;
    width: 100%;
    margin: 0 0 1rem 0;
  }
}