.grid-container-15 {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-rows: auto;
  column-gap: 10px;
}

@media screen and (max-width: 767px) {
  .grid-container-15 {
    grid-template-columns: 1fr;
    grid-template-rows: repeat(3, auto);
    row-gap: 10px;
  } 
}