Each page encapsulates only the subfolders and photos contained within the current folder, contextually concatenated with all the others in the tree...dynamic, and on-the-fly: no database required!
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:
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 reactive at the top of the page.