Re: [csswg-drafts] [scroll-animations-1] Consider initial value of auto for view-timeline-inset (#7747)

The CSS Working Group just discussed `[scroll-animations-1] Consider initial value of auto for view-timeline-inset`, and agreed to the following:

* `RESOLVED: scroll overlap range is in addition to scroll-padding, view-timeline-inset should have an initial value of auto`

<details><summary>The full IRC log of that discussion</summary>
&lt;emilio> flackr: we discussed this in our previous session and resolved that the initial view-timeline-inset should be 0 based on the assumption that scroll-padding was used to set a margin for page-down operations<br>
&lt;emilio> ... but all browsers actually scroll 87% of the remaining area after you remove scroll-padding<br>
&lt;emilio> ... so scroll-padding is strictly used for occluding element<br>
&lt;emilio> ... and changing that would break sites that use it to exclude occluding elements<br>
&lt;Rossen_> q?<br>
&lt;emilio> ... so proposal is to have auto which is scrollport minus scroll-padding<br>
&lt;emilio> ... to account for invisible elements<br>
&lt;emilio> fantasai: one of the goals for scroll-padding was to give the author the ability to control that overlap<br>
&lt;emilio> ... or zero, but I understand we have a compat problem but that brings the question of how we want to address that use case<br>
&lt;fantasai> s/or zero/or set it to zero/<br>
&lt;emilio> flackr: so... the issue is that devs have used it assuming that it's strictly an overlapping-element-region<br>
&lt;emilio> ... if we change the interpretation as offset-defining the page region you change page-down behavior<br>
&lt;emilio> ... I guess it's complicated wrt view-timeline-inset<br>
&lt;emilio> fantasai: I think for view-timeline-inset should just account for padding<br>
&lt;emilio> q+<br>
&lt;emilio> fantasai: that's what auto would do, it should not pay attention to the absolute amount of scroll<br>
&lt;emilio> flackr: developers are using it because we don't use that as the page value<br>
&lt;Rossen_> ack emilio<br>
&lt;fantasai> emilio: I was going to agree with fantasai<br>
&lt;emilio> fantasai: ua should provide some overlap for continuity purposes on top of that<br>
&lt;fantasai> s/ua should/then we need to update the scroll-snap spec to say the ua should/<br>
&lt;emilio> flackr: [on-the-spot compat check]<br>
&lt;fantasai> flackr: Chrome and Safari are using 87.5% of the scroll-padding inset area<br>
&lt;emilio> flackr: firefox is not using scroll-padding at all for page amount, webkit/blink have 87% of scroll-padding<br>
&lt;fantasai> flackr: Firefox is not using scroll-padding at all<br>
&lt;fantasai> emilio: I think scroll-padding should be accounted for<br>
&lt;fantasai> emilio: if we don't, it's an oversight<br>
&lt;fantasai> emilio: It might be we don't want to define as the whole region<br>
&lt;fantasai> emilio: but, we could still not have an auto value<br>
&lt;fantasai> emilio: and use zero and have ?? use scroll-padding area<br>
&lt;fantasai> emilio: I don't care either way, having a zero start or auto<br>
&lt;emilio> flackr: I just remembered the other complication, we use the padding area for how much additional scrolling we need to do to scroll things into view<br>
&lt;emilio> ... so the way it's defined it's better suited to define overlapping elements<br>
&lt;emilio> ... to me that implies it should be fine to have view-timeline follow that as the default<br>
&lt;emilio> fantasai: I think the proposed resolution is: #1, scroll overlap range is in addition to scroll-padding, that requires scroll snap changes<br>
&lt;emilio> ... #2 changing view-timeline-inset to have an initial value of auto<br>
&lt;emilio> RESOLVED: scroll overlap range is in addition to scroll-padding, view-timeline-inset should have an initial value of auto<br>
</details>


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Received on Monday, 20 March 2023 15:03:08 UTC