Each mockup is a self-contained HTML file. Open them in a browser — no server needed for most things. For the feedback "Copy JSON" button to work (clipboard access), serve with a local HTTP server:
Then open http://localhost:8080 in your browser.
How to give feedback:
These are pure HTML/CSS/JS — no framework, no API calls, no build step. Safe to open directly from the filesystem or a simple HTTP server.