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Re: [csswg-drafts] [css-ui] 'auto' as the initial value for the 'appearance' property isn't web-compatible

From: Florian Rivoal via GitHub <sysbot+gh@w3.org>
Date: Fri, 12 May 2017 09:43:46 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-301033093-1494582224-sysbot+gh@w3.org>
Sorry for the slow follow up.

The spec is not expected to be web compatible if used under the webkit prefix.

The different prefixed version by different browsers are different from eachother, as they have a separate value for lots and lots of replaced element / form control / parts of form controls, and they all have a different non standard set of these. It's not just the values of -foo-appearance that are non standards, but the actual things they represent.

Based on this, when drafting the spec for appearance, I concluded (and as far as meetings show, the CSSWG agreed) that what was currently implemented by browsers was not possible to standardize, and that we should try to build a saner thing that actually could be, so that in the long run it would take over. The result is replacing the long list of weird values with a single 'auto' value, and 'none'. Since that's not how the prefixed versions work, I am not surprised that implementing that and aliasing it to -webkit-appearance would be web incompatible.

However, would it still be web incompatible if you did not alias the two?

As far as I can tell, "something sane for all UAs and all platforms" and "something compatible with -webkit-appearance" are mutually exclusive goals.

We could make the change you suggest ('none' as the initial value instead, and override that with 'appearance:auto' in the UA sheet for elements that have a native look), but:
1. I suspect this would not be enough to make the appearance web compatible if aliased with the '-webkit-appearance'
2. It's a a kudge.

If 1. isn't actually true, and that's enough to make it possible to alias appearance and -webkit-appearance and have that be web compatible, maybe it's worth the ugliness.

However, I suspect that it will not and that you (unfortunately) will need to implement a both sane version of appearance, which is something like what's in the spec with more details filled in, and separately implement a -webkit-appearance that you'll be tweaking for years to come as you find more odd sites depending on yet another misunderstood aspect of it.

We should totally also specify that variant, since web compat requires it, but I hope we can also provide a clean and sane path forward to authors.

-- 
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Received on Friday, 12 May 2017 09:43:52 UTC

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