Design Review #663

#663: Review Request for prefers-contrast media query

Opened Aug 4, 2021

Ya ya yawm TAG!

I'm requesting a TAG review of the prefers-contrast media query.

This media feature from Media Queries Level 5 lets authors adapt web content to a user-selected contrast scheme. Keywords: 'more', 'less', 'custom', and 'no-preference'. This feature was previously discussed in https://github.com/w3ctag/design-reviews/issues/583 but the syntax has since changed.

Explainer¹ (minimally containing user needs and example code): see comment
Specification URL: https://drafts.csswg.org/mediaqueries-5/#prefers-contrast
Tests: https://wpt.fyi/results/css/mediaqueries/prefers-contrast.html
Security and Privacy self-review²: https://github.com/w3c/security-request/issues/9
GitHub repo (if you prefer feedback filed there): https://github.com/w3c/csswg-drafts/issues
Primary contacts (and their relationship to the specification):
- @sartang
- @alisonmaher
Organization(s)/project(s) driving the specification: Microsoft, Google, Firefox, Apple
Key pieces of existing multi-stakeholder review or discussion of this specification:
- https://github.com/w3c/csswg-drafts/issues/5224#issuecomment-854066027
- https://github.com/w3c/csswg-drafts/issues/6036#issuecomment-819131784
External status/issue trackers for this specification (publicly visible, e.g. Chrome Status):
- https://www.chromestatus.com/guide/edit/5646323212615680

Further details:

I have reviewed the TAG's Web Platform Design Principles
Relevant time constraints or deadlines: none
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:
This work is being funded by: implementation work by Microsoft, Google, Apple, Mozilla

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

🐛 open issues in our GitHub repo for each point of feedback

Discussions

2021-08-16

Minutes

Rossen: another without an explainer... "see the specification"... this is a differential review based on #583. Having a hard time figuring out what changed.

Tess: I don't understand how this custom value isnt just a rename of the old forced value.

Rossen: we had a long conversation.. with that naming we were able to come around and have good enough consensus in the CSS WG.

Tess: i'm going to post a question in CSS WG issue 5433... most recent conversation at the end of 6036... pinged on that.. there's an implication that operating systems have a pretty big space in between what would match more and what would match less. Some value in having a value that matches in between them. If I read correctly.. windows matches high when it's a contrast ratio of 7:1 or higher, whereas on mac it's 4.5:1 or higher. Maybe it's less clear if there's a value in having that middle value on platforms where high contrast isn't that high? Or low isn't that low. I'm happy to defer to James on what would make sense of any of our platforms.

Rossen: how does that fit into what we're asked to review here?

Tess: I love the comment you already made, asking for an explainer. When they have one it'll be nice to see how they talk about this. I think we can leave it at that.

2021-09-Gethen

Minutes

They wrote a lovely explainer as a comment on our design review issue. Tess asked them to find a more permanent home for it.

Otherwise things look great. Closed with comment.