Piwigo Stock Site Frontend Revamp

My stock-image platform runs on Piwigo, but the default theme no longer reflects the brand. I need the entire frontend redesigned to give visitors a modern, clean experience that feels quick, intuitive, and fully responsive on every screen size.

Here is what I expect:
• A custom Piwigo theme (Smarty templates, CSS, JavaScript) that installs like any other Piwigo theme and keeps core updates intact.
• Consistent typography, whitespace, and colour palette that reads “modern and clean,” with an unobtrusive UI so the images stay centre stage.
• Responsive grids for category, tag and search pages, plus an elegant lightbox or modal for single-image viewing.
• Navigation, upload and checkout flows tested across Chrome, Firefox, Safari and Edge, desktop and mobile.

Time is critical—I’d like to see the first working draft as soon as possible and reach a production-ready version without delay. When you reply, focus on the experience you have customising or building Piwigo (or similar gallery/CMS) themes and show live examples if you can.