.thumbnail img{
  object-fit:contain;
}

@media screen and (max-width: 749px) {
  .thumbnail-list__item.slider__slide{
      width:calc(25% - .6rem);
  }
}

@media screen and (min-width: 750px) {
  .product--thumbnail_slider .thumbnail-slider{
    margin-top:2rem;
  }
}