I think this is intentional so ?printable=yes works? See also T51722: ResourceLoader does not process media queries for printable view with JS-added CSS and T24256: Change printable link to JavaScript `print()`.

In T108413#1520463, @Legoktm wrote:

I think this is intentional so ?printable=yes works? See also T51722: ResourceLoader does not process media queries for printable view with JS-added CSS and T24256: Change printable link to JavaScript `print()`.

T51722 is about JS-added CSS, which this isn't. And I don't see how T24256 is related at all. Am I missing something?

In T108413#1520735, @ori wrote:

Am I missing something?

No, I misunderstood what this bug was about.

Should this be done for just media => print or all media types like screen, etc.?

In T108413#1520962, @Legoktm wrote:

Should this be done for just media => print or all media types like screen, etc.?

Ideally all stylesheets which apply only to specific media will declare their media type. Practically speaking, the benefit will come almost entirely from splitting off media=print stylesheets into a separate link tag.

Change 230487 had a related patch set uploaded (by Legoktm):
Load 'mediawiki.legacy.commonPrint' styles with a media type property

https://gerrit.wikimedia.org/r/230487

In T108413#1520999, @ori wrote:

Ideally all stylesheets which apply only to specific media will declare their media type. Practically speaking, the benefit will come almost entirely from splitting off media=print stylesheets into a separate link tag.

I went with a very simple solution for now by creating a separate 'print' group, and modules that set it will use a separate <style media="print"> tag. This doesn't help for things like mediawiki.action.history.diff which has a media=>print style-sheet and a media=>all style-sheet.

Change 230487 merged by jenkins-bot:
Load 'mediawiki.legacy.commonPrint' styles with a media type property

https://gerrit.wikimedia.org/r/230487

Change 230575 had a related patch set uploaded (by Ori.livneh):
Load 'mediawiki.legacy.commonPrint' styles with a media type property

https://gerrit.wikimedia.org/r/230575

Change 230575 merged by jenkins-bot:
Load 'mediawiki.legacy.commonPrint' styles with a media type property

https://gerrit.wikimedia.org/r/230575