Envira gives you an option with the Base (Dark) and Base (Light) lightbox themes to toggle the lightbox thumbnails on or off for your visitor.
Click this to see the lightbox thumbnails turn on and off. We’ve set the option to have the thumbnails hidden until you click the toggle button for this demo.
Number of Gallery Columns is Automatic with 215px Row Height and 5px margins using the Base (Dark) lightbox theme with the Toggle Thumbnails? option enabled.