Re: [csswg-drafts] [scroll-animations] `ViewTimeline` -> allow to specify scroller (`source`) (#12615)

This is not an oversight.

A subject is _always_ tracked within it’s scroll parent, because under the hood the timelines work with the scroll offset of that scroller. When a ViewTimeline gets created, the necessary offsets for the animation are calculated, and then the timeline is left untouched _(until the scroller or the subject’s geometry changes)_.

Tracking a subject within a different (ancestor) scroller would make it very complicated – and expensive to implement, I guess – because it would result in timelines themselves to constantly change _as you scroll_  any scroller in between the subject and the tracked scroller.

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Received on Tuesday, 19 August 2025 14:57:06 UTC