What this gallery shows
Each form on the front is a composition of form kinds: the build writes the controls and their constraints from the fields' declarations, the page checks what you type by the same rules, and the preview shows the answers back without sending them anywhere.
A demonstration: the gallery is invented and its address goes nowhere. Built by plinth from EDN: the forms are compositions, the controls' rules are written from the fields' declarations, the preview and the email are the page's own work, and nothing is sent from the site.