@media all and (min-width: 481px) {
  .category-promotion .item-box {
    width: 32%;
    text-align: center;
  }

    .category-promotion .item-box:nth-child(2n+1) {
      margin-left: 2%;
      clear: none;
    }

    .category-promotion .item-box:nth-child(3n+1) {
      margin-left: 0;
      clear: both;
    }
}