.grid-gallery-flex {
    box-sizing: border-box;
    display: flex;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}
.col3 {
    flex: 1 1 32%;
    padding: .5%;
    width: 33%;
}
.col3 img {
    width: 100%;
}
.col3:nth-of-type(3n+3) {
      margin-right: 0;
}
@media all and (min-width: 550px) and (max-width: 775px){
      .col3 {
          /* width: 49%; */
      }
      .col3:nth-of-type(odd){
          /* margin-right: 2%; */
      }
      .col3:nth-of-type(even){
          /* margin-left: 0; */
          /* margin-right: 0; */
      }
  }
@media all and (max-width: 549px){
    .col3 {
        flex-basis: 49%;
    }

  }