Increase Gallery thumb size and reduce columns from 4 x 100px to 3 x 250px

Woocommerce Gallery Thumbnail Sizes

<?php
// Set gallery thumbnail size
// Run Regenerate Thumbnails if size is not defined in media
function woo_gallery_thumb_size( $size ) {
	return array(
		'width'  => 250,
		'height' => 250,
		'crop'   => 1,
	);	
}

add_filter( 'woocommerce_get_image_size_gallery_thumbnail', 'woo_gallery_thumb_size' );
?>


/* Custom CSS */
/* convert 4 image galler to 3 */

.woocommerce div.product div.images .flex-control-thumbs li {
    max-width: 100% !important;
    width: 33%;
}

.woocommerce div.product .woocommerce-product-gallery--columns-4 .flex-control-thumbs li:nth-child(4n+1) {
    clear: none;
}
.woocommerce div.product .woocommerce-product-gallery--columns-4 .flex-control-thumbs li:nth-child(3n+1) {
    clear: left;
}