add images to acf post object in admin area

// add images to admin post object
function my_post_object_result( $title, $post, $field, $post_id ) {

	if ($post->post_type == 'product') {

		global $nf;

		$title = '<div class="prodi" style="background-image: url(' . $nf->image(wp_get_attachment_url( get_post_thumbnail_id( $post->ID ) ), 140, 140) . ');"></div>' . $title;

		$title = '<div class="prodc">' . $title . '</div>';

		return $title;
	}

}
add_filter('acf/fields/post_object/result', 'my_post_object_result', 10, 4);

// add images to admin post object - css
add_action('admin_head', 'fields_custom_styles');
function fields_custom_styles() {
	echo '
		<style type="text/css">

			.ui-sortable .prodi {
				background-color: #fff;
				background-position: 50% 50%;
				background-repeat: no-repeat;
				background-size: contain;
				height: 140px;
				width: 140px;
			}

			.ui-sortable .prodc {
				font-size: 11px;
				overflow: hidden;
				padding-bottom: 2px;
				width: 140px;
			}

		</style>
	';
}