Collapse

What collapses. Their natural height is what the animation measures, so a child of its own animated height fights it; the wrapper element this component adds is always present.

Lands on the animated element, after the classes the style props generate.

Swaps the default spring for a tween of this many milliseconds. The spring is the better fit for content of unknown height; reach for a fixed duration when the opening has to line up with another animation.

Whether the block is open. Closed is not unmounted: the children stay in the DOM, marked `aria-hidden` and `inert`, so they are out of the accessibility tree and out of the tab order while keeping their state.

Inline styles on the animated element; they beat the style props. Setting `overflow` here overrides the `hidden` the component applies, and the content spills out mid-animation instead of being clipped.