How to change numbers of column in a row in a portfolio layout grid:simple?

@CdVstudio Hi! You can add this code under Website > Pages > Website Tools > Custom CSS

@media screen and (min-width: 1025px) {
    #gridThumbs {
      display: flex !important;
      flex-wrap: wrap;
      gap: 40px;
    }

    .grid-item {
      flex: 0 0 100%; 
    }

    .grid-item:nth-child(2), .grid-item:nth-child(3) {
      flex: 0 0 calc(50% - 40px);
    }

    .grid-item:nth-child(4), .grid-item:nth-child(5), .grid-item:nth-child(6) {
      flex: 0 0 calc(33.333% - 40px); 
    }
}