Four ways to arrive

The shipped masthead assembles into a fixed bar once the page scrolls past its origin. What that assembly should look like was the open question. 00 is the answer that shipped, rendered with the live component, and it is the only one here that cannot go stale. 03 archives the bar's earlier motion as a frozen copy; 01 and 02 never became components at all. All three archives are snapshots, so read them against 00 rather than on their own.

Each one needs a scroll to show itself — the masthead is not meant to announce itself on arrival. The page bodies are measured scaffolding rather than real content, marked off in viewport heights so you can see where each variant triggers. Scroll past the heading and back up again to see the whole movement.