If you don’t like how your current theme is displaying the filters, or you are migrating from a different plugin and you want your filters to look the same as they did before, add the CSS Class here.

If you are migrating from another plugin, the CSS classes that are commonly used are below – if you wish to maintain the look of your existing widgets, probably adding these classes will do that for you:

woocommerce widget_layered_nav widget_product_categories