The Power add on provides settings for the CSS classes that are used to wrap the Pages list elements when rendering the slp_pages shortcode.
By default the pages list is wrapped in a div with class slp_pages_list.
Each list entry within is then inside a div with the slp_page location_details class.
This set of instructions will require you to be using the MySLP Professional level of service or higher. The Professional level includes the Experience add on that provides the Custom CSS rules interface. Instructions here are specific to MySLP but will work for WordPress plugin users as well.