Re: [csswg-drafts] [css-variables] User Agent properties and variables

OK so I’ve been following this issue for a while and there are some details for which I’d like clarifications if possible. Sorry if some were addressed or implied (and cc-ing @dauwhe and @TzviyaSiegman since that will probably impact the Publishing Working Group and the personalization Task Force at some point). 

The first question is quite simple: who will be able to create and set those constants?

For instance, I assume `user-font-size` could be set based on the iOS a11y preference or a browser setting, and `user-background-color` based on high contrast mode in Windows 10. 

But what if you have an intermediary layer managing documents like, say iBooks or Google Play Books? They have sepia and night modes, their own font-size user setting, and a couple of extras options which OSs and browsers might not offer (`text-align`, hyphens, `line-height`, dyslexia typeface, etc.). 

I guess that if the apps are using a web view, they might be able to create and set them. Correct? But what about cloud versions? 

Sorry if that is unclear to me, I was kinda super happy when I discovered this proposal as it could help with user settings (both apps and authors) and I guess I need an answer as whether this could fit in there or not. To be fair, this should probably be global variables since they will change at runtime. 

On a related note, PDF version 2 is using HTML and CSS to make documents more accessible, so PDF apps might offer such options at some point (and PDF is still a popular format).

Another question: how will this possibly relate to [COGA Semantics to Enable Personalization](https://w3c.github.io/personalization-semantics/)?

People might not like Reading Systems (and I kinda get the reasons why), but if it proved anything, it’s that when user settings have a GUI in the app’s chrome, user will override a lot of authors’ styles (and expect those user settings to be available). On the other hand, authors tend to hate when their entire stylesheet is removed (reader modes, which sometimes fail spectacularly with more than basic documents). 

Consequently, I can clearly see how User Agent properties could help, although the burden would be put on authors. Now, this proposal deals with user settings ([but this section is not yet developed](https://w3c.github.io/personalization-semantics/#user-settings)), so back to the first question.

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Received on Friday, 15 September 2017 10:13:23 UTC