.box {
  margin: 5px;

  @media screen and (min-width: 576px) {
    max-width: 100%;
  }

  @media screen and (min-width: 768px) {
    max-width: 80%;
    margin: 15px;
  }

  @media screen and (min-width: 992px) {
    max-width: 50%;
  }
}