Re: [csswg-drafts] [css-contain-3][css-animations][css-transitions] Isolate animation side-effects? (#6398)

Thanks for having a look @birtles.

> I'm not sure about this. It's been a while since I've touched this code but from memory the following clause from the CSS Transitions spec is quite important: [...]

Note that I'm redefining the before-change style to be the before-change _base_ style, and the same for the after-change style. The base style does not include _any_ animation/transition effects of any kind, hence the current time of existing animations is not relevant for the purposes of triggering transitions.

> I think Firefox should be correct regarding the before/after change styles part including inheritance--the only area where I'm aware it's wrong is with regards to context-sensitive properties like font-size.

I don't doubt that the fundamentals are correct in Firefox. For example I see that all levels are correctly transitioning at the same time [in this example](https://jsbin.com/coguyeroya/1/edit?html,output). (Not the case in Chrome).

But more interesting are the parts that would be affected by this change, e.g. "complex" inherited interaction between ongoing animations and transitions, [as in this example](https://jsbin.com/qenasuvilu/edit?html,output), where no browser gets it right. With this proposal, there would be no transition on `#inner` at all, since its before/after-change (base) styles are unaffected by animations on `#outer`, and therefore the before/after-change styles are equal.

Not sure what the full implications of this change would be, and if any losses would be worth it if we gain container queries.

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Received on Tuesday, 22 June 2021 09:57:20 UTC