CSS for the MarketPress e-Commerce plugin for WordPress to display products in a 3-column grid format.

marketpress-global-product-grid.css

div#mp_product_list .product {
  display: inline;
  float: left;
  width: 29%;
  margin: 2%;
}

div#mp_product_list .product:nth-child(3n+1) {
  clear: both;
}

@media all and (max-width: 800px) {
  div#mp_product_list .product {
    width: 46%;
    margin: 2%;
  }
  div#mp_product_list .product:nth-child(3n+1) {
    clear: none;
  }
  div#mp_product_list .product:nth-child(2n+1) {
    clear: both;
  }
}

@media all and (max-width: 500px) {
  div#mp_product_list .product {
    width: 100%;
    margin: 0;
  }
}

div#mp_product_list .product img.alignleft, .entry-content .wp-caption.alignleft {
  margin-left: 0px; /* image alignment adjustment for Twenty-Thirteen theme */
}