@media only screen and (min-width: 768px) {
  .half {
    display: flex;
  }
  .half > div {
    width: 50%;
    padding: 1em;
  }
}
@media only screen and (max-width: 767px) {
  .half {
    display: flex;
    flex-wrap: wrap;
  }
  .half > div {
    width: 100%;
    padding: 1em;
  }
}