Re: [csswg-drafts] [css-color-adjust-1] What happens with multiple <meta>s? (#3846)

The CSS Working Group just discussed `What happens with multiple <meta>s?`.

<details><summary>The full IRC log of that discussion</summary>
&lt;dael> Topic: What happens with multiple &lt;meta>s?<br>
&lt;dael> github: https://github.com/w3c/csswg-drafts/issues/3846<br>
&lt;dael> TabAtkins: Meta name = color-scheme lets you set initial color-scheme so we can get that value out quick. What happens if you use multiple? Two obvious are take hte first or take the last valid one. Precedent both ways<br>
&lt;dael> TabAtkins: I propose we take the first so we get the value as quickly as possible so don't have to wait for rest of page to load before we apply effects<br>
&lt;dael> AmeliaBR: Since whole point of meta is to get it asap it does make sense. We have examples in HTML that are consistent<br>
&lt;dael> TabAtkins: theme value also takes the first so it's consistent that way<br>
&lt;dael> fantasai: I would consider multiple to be an error case. If you're flipping colors constantly that's  your fault. I think it benefits authors if we're consistent and agree with smfr it should be one rule for all meta tags<br>
&lt;dael> fantasai: Given oldest is viewport that means using last one<br>
&lt;dael> TabAtkins: Using last for viewport gives the bad behavior you listed. I think viewport fell out of viewport defined as eq to a stylesheet<br>
&lt;dael> fantasai: It's an error case. If author wants correct they should not ut multiple. I think it's fine if broken isn't correct. Consistant story for authors is more important that it's always last. Arbiraryness is more disruptive then having to keep all the things<br>
&lt;dael> TabAtkins: But if we have to take last, we can't render until have downloaded enough of HTML. I agree with consistency argument. I'd like to be consistent with first and see if we can adjust viewport.<br>
&lt;smfr> q+<br>
&lt;dael> fantasai: If you want to go that route it's fine. i think it's important we're consistent. If you want to see first is web compat that's good.<br>
&lt;dael> astearns: Sounds like we already have different. I'm concerned about hitching consistency to viewport given comment from futhark that viewport is last one inserted into doc.<br>
&lt;dael> TabAtkins: Yeah, ours is messed up. We shoudl not rely on viewport<br>
&lt;astearns> ack smfr<br>
&lt;dael> smfr: before that comment I was reluctant on viewport. Changing viewport now does have more web compat concerns. I would love all meta tags to have sam.e need to figure out dynamically inserted nodes<br>
&lt;dael> smfr: UA might not process meta tags until end of head. Just because you have multiple doesn't mean you'll see flashes, UA can wait until end of head.<br>
&lt;myles> q+<br>
&lt;dael> TabAtkins: Certainly can, but end of head could be different packet and flush the queue. Definitely different behaviors allowed.<br>
&lt;astearns> ack myles<br>
&lt;fantasai> s/rely on viewport/rely on viewport behavior/<br>
&lt;dael> myles: Procedurally meta tag is defined in HTML. If we decide something here is there anyone that can make edits to resolve this?<br>
&lt;AmeliaBR> We are currently defining the meta value: https://drafts.csswg.org/css-color-adjust-1/#color-scheme-meta<br>
&lt;dael> TabAtkins: Should try and get agreement on consitent behavior and get that into general meta authoring guidelines<br>
&lt;dael> astearns: But this needs to be spec elsewhere<br>
&lt;dael> TabAtkins: Yes, actual definition is in HTML. They are deferring to us on this since we're defining it<br>
&lt;dael> astearns: I'm assuming that for web compat reasons we're not going to be able to change current viewport. Given that would anyone object to spec that the color-scheme meta will match theme-color and take first one found?<br>
&lt;dael> smfr: What happens with other meta like char-set?<br>
&lt;dael> TabAtkins: I do not know. But those are also more super legacy and likely to be weird<br>
&lt;dael> astearns: Would be nice to have answer<br>
&lt;dael> smfr: Agree.<br>
&lt;dael> fantasai: Don't want to resolve without jen or rachel<br>
&lt;dael> astearns: Fair<br>
&lt;dael> fantasai: I believe impact to author is bigger concern then get the earliest possible<br>
&lt;dael> TabAtkins: We've got 2 css things that are inconsistent so we'll have to change something. Maybe we have a new policy and legacy is legacy.<br>
&lt;dael> fantasai: If it's completely inconsistent and we can't align I'm fine with a going forward policy. If it's possible to align them all we should go that way<br>
&lt;fantasai> Or even to align most of them<br>
&lt;dael> astearns: TabAtkins can I ask you to do survey of meta tags that effect css?<br>
&lt;dael> TabAtkins: Looking at it. It's a consiquence of algo and not states so I'm chasing it down<br>
&lt;dael> astearns: let's wait on this issue until we get the survey and comments from authoring advocates. Sound good?<br>
&lt;dael> TabAtkins: mmhmm<br>
</details>


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Received on Wednesday, 19 June 2019 16:39:01 UTC