These components are HTML, not a framework app. There is no build step, no virtual DOM, and no client-side templating. The markup is the component; Datastar attributes make it reactive, and system.css styles it (static/system.css — read the system-css skill). State lives in signals, not in form fields — with the land-and-stream qualifier stated up front: signals hold COMPONENT-EPHEMERAL state (draft, hover, shown month) and act as TRANSPORT for commands; anything a view renders is STORE truth, and a fat-morph re-merging a signal server-authoritatively is correct behavior, not a bug. Every component below is the same small shape — learn it once.
Read the system-css skill for the styling engine (--bg/--fg/--type, primitives, the surface contract). This skill is only about wiring Datastar onto it.