[css-scroll-snap] Clarify what the expected animation behavior on scroll-margin and scroll-padding

[hiikezoe]

Those properties are defined as animatable by computed value, but its outcome is unclear to me. Given that these properties don't change layout, browsers don't need to re-snap? I am asking because there's an interesting bug report, https://bugzilla.mozilla.org/show_bug.cgi?id=1816003 .

[fantasai]

Interesting indeed. :) My expectation is that if scroll-margin is animating while you're snapped to that element, then the scroll position changes in accordance with the animation, so that at any given point in time the layout of the page (and the scroll positions) match what would happen if you loaded the page with those settings. There may be limits to what's practical from an implementation perspective, but in general CSS is stateless and what you get is what the current state of the properties dictate.