A folder or sub-folder is represented by a "manilla-folder" thumbnail with badges showing the quantity of contents. Click/touch any folder image to proceed further into subfolders. Orange counters indicate the # of sub-folders; green counters indicate the # of images; both, together, indicate the # of sub-folders and the # of images contained, therein. A thumbnail of every image in the current subfolder is automatically created if it does not already exist, each linking to a larger version in a touch-enabled fancybox 'lightbox'

Once you click/touch an image, you can then navigate through the sub-gallery in any of three ways:

• Use the arrow keys (↑→↓←) on your keyboard
• Click/touch to the left/right of the image
• Swiping with your finger (or toe (or nose, for that matter)) left, right, up or down on a touch-enabled device

Close the image-preview with the [esc] key, or with the X in the top-right corner

Navigation context (e.g., "breadcrumb trail", "link-back-to", etc.) is interactive at the top of the page

Image processing in Photoshop; graphic design in Affinity Designer

Primary source derived (and extensively modified using BBEdit on a Mac Pro) from Harry Ghazanian's most-excellent folioGallery (v.1.4)

Thanks, Harry