#881: `prefers-reduced-transparency` CSS Media Query

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Opened Aug 2, 2023

こんにちは TAG-さん!

I'm requesting a TAG review of CSS prefers-reduced-transparency.

The prefers-reduced-transparency media feature is used to detect if the user has requested the system minimize the amount of transparent or translucent layer effects it uses.

Further details:

  • I have reviewed the TAG's Web Platform Design Principles
  • Relevant time constraints or deadlines: n/a
  • The group where the work on this specification is currently being done: CSSWG
  • The group where standardization of this work is intended to be done (if current group is a community group or other incubation venue): CSSWG
  • Major unresolved issues with or opposition to this specification: adds a fingerprinting vector
  • This work is being funded by:

We'd prefer the TAG provide feedback as (please delete all but the desired option):

💬 leave review feedback as a comment in this issue and @-notify @lukewarlow

Discussions

Comment by @cookiecrook Oct 2, 2023 (See Github)

@lukewarlow wrote:

Organization(s)/project(s) driving the specification:

and

Major unresolved issues with or opposition to this specification: adds a fingerprinting vector

Additional context on why this isn't implemented in WebKit yet found in WebKit Position #145 and CSS #8651 (quoting from the latter):

Note on Fingerprinting

[ Several proposed media features, including this one] are subject to changes based on the outcome of https://github.com/WebKit/standards-positions/issues/145 and other related privacy issues. We debated not proposing https://github.com/w3c/csswg-drafts/issues/8651 until after privacy issues with @media/matchMedia() had been resolved, but decided to propose it here anyway to further the discussion.

Discussed Oct 9, 2023 (See Github)

Peter: same as 883

Rossen: did we resolve on the syntax..?

Lea: webkit has a standards position against this because it adds a fingerprinting vector...

Yves: I tried to look at this and it's not properly explained. I couldn't figure out what is exposed more by using this. Apart from the fact that you're supporting that in the browser

Peter: one more bit of entropy for the user if the user has this setting turned on. Also true of 883.

Lea: accessibility needs outweigh tiny fingerprinting surface..

Peter: worth pausing to ask if there's a way to mitigate. In this case the benefit is worth the cost.

<blockquote>

We're happy to see this moving forward, so we will close this. As part of the review we also looked at the fingerprinting concerns raised by WebKit. Our opinion is that the user benefit outweighs the privacy concern. That said, exploring ways to mitigate this more generally without negatively impacting user experience, especially of users with accessibility needs, would be welcome.

Thank you for flying TAG!

</blockquote>
Comment by @LeaVerou Oct 9, 2023 (See Github)

Hi all,

We reviewed this during a breakout today.

We're happy to see this moving forward, so we will close this. As part of the review we also looked at the fingerprinting concerns raised by WebKit. Our opinion is that the user benefit outweighs the privacy concern. That said, exploring ways to mitigate this more generally without negatively impacting user experience, especially of users with accessibility needs, would be welcome.

Thank you for flying TAG!