.products-container { position: relative; }
.product { width: 24%; margin-bottom: 16px; }  /* ~4 columns on desktop */
.productimg { width: 100%; height: auto; display: block; }

@media (max-width: 1200px) { .product { width: 32%; } }  /* 3 cols */
@media (max-width: 900px)  { .product { width: 48%; } }  /* 2 cols */
@media (max-width: 600px)  { .product { width: 100%; } } /* 1 col */