Reveal

How much of the element has to be visible before it fires, from 0 to 1. Keep it low for tall blocks: an element taller than the viewport can never reach a high threshold, and would never reveal at all.

What is revealed. It is never hidden by the stylesheet: the hidden state is applied from the client only once motion is known to be allowed, so with JS off, without an `IntersectionObserver`, or under reduced motion the content is simply there.

The element it paints. It swaps the root for its animated twin rather than wrapping it, so this component adds no node — which is what lets it sit between a grid and its items.

Length of the entrance in milliseconds. Ignored when `spring` is set.

Position in a stagger, which delays this one relative to its siblings. Pass the map index over a list; the delay is capped, so a long list does not end with an element waiting seconds.

Whether it reveals once and stays. Turning it off makes content re-animate every time it re-enters the viewport, which reads as flicker on a page the user scrolls back up.

Which way it enters. Same seven presets as `Transition`, with a different trigger: that one fires on `mounted`, this one on coming into view.

The observer's root margin. The default pulls the trigger line 10 % up from the bottom edge, so the entrance starts before the element is flush with the fold rather than after.

Uses a theme spring instead of a tween, which leaves `duration` unread.