Re: [csswg-drafts] [css-sizing][responsive-iframe] Should `frame-sizing` apply to SVG contents? (#13588)

The CSS Working Group just discussed ``[css-sizing][responsive-iframe] Should `frame-sizing` apply to SVG contents?``, and agreed to the following:

* `RESOLVED: Currently SVG in iframe doesn't respond to frame sizing (because you can't opt it in)`

<details><summary>The full IRC log of that discussion</summary>
&lt;Rossen> github, take up https://github.com/w3c/csswg-drafts/issues/13588<br>
&lt;emilio> koji: so frame-sizing was discussed on the last f2f, I've updated the spec in response to that discussion<br>
&lt;emilio> ... filed three issues with some investigation I did<br>
&lt;emilio> ... I didn't see clear preferences either way on whether to apply to SVG<br>
&lt;emilio> ... SVG has some magic behavior<br>
&lt;emilio> ... they have use cases so I'd prefer not to mess with that<br>
&lt;emilio> q+<br>
&lt;TabAtkins> +1<br>
&lt;TabAtkins> emilio: When you  say 'applyl to SVG', I think SVG only has magic for object and embed<br>
&lt;TabAtkins> emilio: do you mean only apply it to iframe?<br>
&lt;Kurt> q+<br>
&lt;TabAtkins> emilio: or to object/embed too, but not when they're SVG?<br>
&lt;TabAtkins> koji: object/embed is another issue, i propose only iframe<br>
&lt;Rossen> ack emilio<br>
&lt;emilio> koji: my proposal is only for iframe<br>
&lt;fantasai> TabAtkins: question is about whether to apply frame-sizing to SVG in &lt;iframe><br>
&lt;fantasai> emilio: Currently it uses 300 x 150 default<br>
&lt;fantasai> emilio: If the overall proposal applies to iframes ...?<br>
&lt;fantasai> TabAtkins: SVG doc in an &lt;iframe>. Not &lt;object><br>
&lt;fantasai> emilio: There's no magic behavior there.<br>
&lt;fantasai> TabAtkins: So should we introduce the magic behavior into the &lt;iframe><br>
&lt;fantasai> emilio: No it should behave like an HTML doc<br>
&lt;fantasai> emilio: I think what Koji's proposing is that SVG inside an &lt;iframe> is not magic, so it doesn't get special behavior when `frame-sizing` is used<br>
&lt;fantasai> emilio: If SVG opted in via this method, then it would get the same behavior as HTML.<br>
&lt;fantasai> emilio: So no auto-magic measuring for SVG.<br>
&lt;Rossen> ack Kurt<br>
&lt;fantasai> PROPOSED: `frame-sizing` has the same effect on SVG in &lt;iframe> as it does for HTML in &lt;iframe><br>
&lt;emilio> Kurt: I think it's best to resolve that<br>
&lt;emilio> ... SVG behaves more like images except for &lt;iframe><br>
&lt;emilio> PROPOSED: SVG documents in iframes don't have frame-sizing effect<br>
&lt;fantasai> TabAtkins: SVG doesn't have meta tags so can't opt into special behavior<br>
&lt;fantasai> emilio: You can put a meta tag into an SVG.<br>
&lt;fantasai> [ discomfort ]<br>
&lt;fantasai> emilio: Meta with color-scheme works.<br>
&lt;fantasai> TabAtkins: It does?<br>
&lt;fantasai> PROPOSED: frame-sizing on an iframe only works for HTML documents<br>
&lt;Rossen> ack fantasai<br>
&lt;emilio> fantasai: I feel like if you manage to opt it in, shouldn't it work the same way?<br>
&lt;emilio> ... why would we make SVG documents different just because it's svg?<br>
&lt;emilio> +1<br>
&lt;fantasai> TabAtkins: can't opt it in<br>
&lt;fantasai> TabAtkins: [because rules]<br>
&lt;emilio> TabAtkins: because frame sizing only applies until `&lt;/head>`<br>
&lt;emilio> fantasai: but the opt in not working is different from the property doesn't apply<br>
&lt;TabAtkins> (even with &lt;html:meta> in SVG, the meta is "frozen" early (by the end of &lt;/head>) and there is no &lt;head> in SVG to scope its parsing to)<br>
&lt;emilio> TabAtkins: we're resolving it's not a problem for now, i.e., there's no way for an SVG doc to get frame-sizing behavior<br>
&lt;fantasai> `frame-sizing` does not have an effect on SVG that hasn't opted in (which it currently can't)<br>
&lt;TabAtkins> (Unlike other &lt;html:meta>s like color-scheme)<br>
&lt;emilio> PROPOSED: Currently SVG in iframe doesn't respond to frame sizing (because you can't opt it in)<br>
&lt;emilio> RESOLVED: Currently SVG in iframe doesn't respond to frame sizing (because you can't opt it in)<br>
&lt;fantasai> +1 emilio<br>
</details>


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Received on Tuesday, 31 March 2026 20:11:40 UTC