[css-2025][mediaqueries-5] Add Media Queries 5 to Rough Interop

[SebastianZ]

Splitting the discussion from #9793 for adding Media Queries 5 to the Modules with Rough Interoperability section of the CSS Snapshot 2025.

Data to consider:

Current status: WD (last published: 18 December 2021), ED from 28 August 2025
WPT: passing tests: Chrome: 93, Edge: 97, Firefox: 89, Safari: 91; interop: 87 / 107 (81.3%)
Current Snapshot section: -
Open issues: on GitHub: 93 (~47 substantial for this spec. level), in spec.: 10

Summary: High interoperability, though many open issues. Looks like WPTs for some features are missing, but some important ones are there. Though as not all features are supported by browsers, maybe only the interoperable ones should be added to Safe to Release pre-CR Exceptions.

Sebastian

[css-meeting-bot]

The CSS Working Group just discussed [css-2025][mediaqueries-5] Add Media Queries 5 to Rough Interop, and agreed to the following:

• RESOLVED: close, no change

The full IRC log of that discussion

<astearns> ack ChrisL
<Zakim> ChrisL, you wanted to wonder who the real editors of MQ5 are
<emeyer> ChrisL: We have a long list of editors and not sure how many are real
<TabAtkins> yeah that's just me and florian, then
<emeyer> florian: I’m no longer funded to work on this, so I’m real but not active
<emeyer> SebastianZ: test coverage is at 81%; a lot of open issues, with about 50 substantial to the spec level; 10 within the spec
<emeyer> …some WPTs are still missing, but the important ones are there
<ChrisL> q+ to say inline <wpt> would be super helpful here
<emeyer> …not all features are supported by all browsers, but the main ones are
<florian> q+
<emeyer> …it could be the whole spec goes to Rough Interop, or we could break things down by feature
<astearns> ack ChrisL
<Zakim> ChrisL, you wanted to say inline <wpt> would be super helpful here
<TabAtkins> Agree, I think this would both benefit from inline wpt, and be appropriate for cherry-picking
<emeyer> ChrisL: THis is a case where because the spec doesn’t have inline WPT annotations, it’s hard to know what’s tested/implemented and which not
<emeyer> …I suspect there are some that are very widely supported, and some not
<emeyer> florian: I agree, and also some features are very hard to test
<emeyer> …All browsers are able to parse the thing and respond, but you can’t always tell if they do the right thing
<emeyer> …We probably need to do a slow walk through here to figure out which things are supported and which are nto
<emeyer> s/nto/not/
<emeyer> …Stuff like environment blending probably not well supported
<emeyer> SebastianZ: Sounds like I should take these back and propose specific features to go to the safe section
<emeyer> florian: Agreed
<emeyer> …Want to also ask what we do about media-queries-4
<emeyer> …I don’t know if we have figured out how to test if the right behavior is happening
<emeyer> …We haven’t really done anything with this in a long time and that’s not good
<emeyer> …I don’t think the tests are good enough
<emeyer> SebastianZ: The next section for level 4?
<emeyer> florian: I think it’s probably ready, but we haven’t checked if browsers are doing what they should
<emeyer> ChrisL: This is work later in the year, not for the snapshot
<emeyer> astearns: Luke Warlow is listed as an editor for level 5
<emeyer> …Maybe Luke could work on tests for level 5, or have ideas on how they could be tested
<emeyer> florian: We have to think it through as a group
<emeyer> astearns: Do we leave open, or close no change?
<emeyer> florian: I think close no change, with an action on SebastianZ to triage issues
<emeyer> SebastianZ: Agreed
<emeyer> RESOLVED: close, no change