#showroom-page {row-gap: 6rem;}

.showroom_p-group h2 {
    position: sticky;
    top: 6rem;
    grid-column: 1/-1;
    margin-bottom: 1rem;
    z-index: 20;
}
.showroom_p-group .product-block:not(:last-of-type) {margin-bottom: 4rem;}

@media only screen and (min-width: 768px) {
    #showroom-page {row-gap: 12rem;}
    .showroom_p-group h2 {margin-bottom: 2rem;}

    #showroom-page .product-block {grid-column: span 4;}
    .showroom_p-group .product-block:not(:last-of-type) {margin-bottom: 6rem;}
}