Intent to Ship: CSS quotes property - support 'auto' value

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Rune Lillesveen

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Aug 20, 2020, 8:31:06 AM8/20/20
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Contact emails

fut...@chromium.org


Specification

https://www.w3.org/TR/css-content-3/#quotes

TAG review

Simple change to established CSS standard, shipped in Firefox, no TAG review should be necessary.

Summary

Support 'auto' for the 'quotes' property. CSS2 specified the initial value for 'quotes' as UA dependent, but WebKit and Blink currently return an invalid value (empty string) for computed style which will not round-trip. Setting it to the empty string will remove the declaration instead of setting it to the initial value. css-content-3 instead uses an 'auto' keyword for the default UA behavior.

Motivation

Fix brokenness in current implementation and align with spec and Firefox.

Risks



Interoperability and Compatibility

The 'auto' value was shipped in Firefox 70.

Interop
Improved with Firefox, worse with WebKit, but considering the current uselessness of the invalid value returned by Blink/WebKit, the current interop is not really that valuable.

Compat
  • Setting the value to initial does not change, the behavior of auto is the same as with the current internal initial representation.
  • Current sites adding a declaration with 'auto' will change behavior to what happens in Firefox. Not likely that this is common.
  • Firefox got a report for the interop issue according to: https://bugs.chromium.org/p/chromium/issues/detail?id=990557#c8
Expected low risk for both interop and compat.

Gecko: Shipped/Shipping (https://developer.mozilla.org/en-US/docs/Web/CSS/quotes#Browser_compatibility) Shipped in Firefox 70 according to MDN.

WebKit: No signal Not responded to reported issue: https://bugs.webkit.org/show_bug.cgi?id=215646

Web developers: No signals


Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?

Yes

Is this feature fully tested by web-platform-tests?

Yes

Domenic Denicola

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Aug 20, 2020, 10:35:40 AM8/20/20
to Rune Lillesveen, blink-dev
Does this change include changing the default user agent stylesheet to no longer match https://html.spec.whatwg.org/#quotes? If so, it would be ideal to get that spec changed; I asked the CSSWG about that some months ago in https://github.com/w3c/csswg-drafts/issues/4074#issuecomment-628161036 but did not get a response.

Emilio Cobos Álvarez

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Aug 20, 2020, 10:49:38 AM8/20/20
to Domenic Denicola, Rune Lillesveen, blink-dev
On 8/20/20 4:35 PM, Domenic Denicola wrote:

> Does this change include changing the default user agent stylesheet to no longer match https://html.spec.whatwg.org/#quotes? If so, it would be ideal to get that spec changed; I asked the CSSWG about that some months ago in https://github.com/w3c/csswg-drafts/issues/4074#issuecomment-628161036 but did not get a response.

Yeah, no browser behaves like the HTML spec says. Such an stylesheet
would be extremely inefficient, so the spec should just be changed to
maybe define what quotes: auto does for a given language.

 -- Emilio

Rune Lillesveen

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Aug 20, 2020, 11:01:20 AM8/20/20
to Emilio Cobos Álvarez, Domenic Denicola, blink-dev
If I read the meeting notes in the github issue correctly, it sounds like the intention was to change the UA sheet in HTML to 'auto' and possibly specify the 'auto'-behavior in CSS, not tied to HTML specifically.

Rune Lillesveen

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Aug 20, 2020, 11:03:27 AM8/20/20
to Emilio Cobos Álvarez, Domenic Denicola, blink-dev
... and since 'auto' is the initial value, it might not be necessary with UA styles at all?

 

Domenic Denicola

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Aug 20, 2020, 11:05:46 AM8/20/20
to Rune Lillesveen, Emilio Cobos Álvarez, blink-dev
From: Rune Lillesveen <fut...@chromium.org>

> If I read the meeting notes in the github issue correctly, it sounds like the intention was to change the UA sheet in HTML to 'auto' and possibly specify the 'auto'-behavior in CSS, not tied to HTML specifically.
>
> ... and since 'auto' is the initial value, it might not be necessary with UA styles at all?

Yes, that might be the case. I just wish someone would engage with the HTML Standard on this, or at least with the HTML Standard's editors, so that we could have the UA stylesheet be correct, and have the specs match what you're proposing to ship here.
 

Rune Lillesveen

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Aug 27, 2020, 7:11:23 AM8/27/20
to Domenic Denicola, Emilio Cobos Álvarez, blink-dev

Rune Lillesveen

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Aug 27, 2020, 7:13:37 AM8/27/20
to blink-dev
On Thu, Aug 20, 2020 at 2:30 PM Rune Lillesveen <fut...@chromium.org> wrote:

Interoperability and Compatibility

The 'auto' value was shipped in Firefox 70.

Interop
Improved with Firefox, worse with WebKit, but considering the current uselessness of the invalid value returned by Blink/WebKit, the current interop is not really that valuable.

Compat
  • Setting the value to initial does not change, the behavior of auto is the same as with the current internal initial representation.
  • Current sites adding a declaration with 'auto' will change behavior to what happens in Firefox. Not likely that this is common.
  • Firefox got a report for the interop issue according to: https://bugs.chromium.org/p/chromium/issues/detail?id=990557#c8
Expected low risk for both interop and compat.

Gecko: Shipped/Shipping (https://developer.mozilla.org/en-US/docs/Web/CSS/quotes#Browser_compatibility) Shipped in Firefox 70 according to MDN.

WebKit: No signal Not responded to reported issue: https://bugs.webkit.org/show_bug.cgi?id=215646

Updated info for WebKit: Emilio landed a fix for the mentioned issue, so all three engines should be aligned if this ships in Chrome.

Daniel Bratell

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Aug 27, 2020, 10:02:53 AM8/27/20
to Rune Lillesveen, blink-dev

LGTM1

/Daniel

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Yoav Weiss

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Aug 27, 2020, 10:15:34 AM8/27/20
to Daniel Bratell, Rune Lillesveen, blink-dev

Chris Harrelson

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Aug 27, 2020, 11:57:17 AM8/27/20
to Yoav Weiss, Daniel Bratell, Rune Lillesveen, blink-dev
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