[mediaqueries-5] Media query for enclosed screens

One key question about devices with virtual headset displays is, in what ways would an author need to adapt their website to accommodate, and do we have media queries for that?

We have hover, pointer, and environment-blending, which address many of the adjustments that might be necessary...

But another one of the functional differences between physical displays and virtual displays is that they're only visible to the user's eyes: nobody else can look over, and also neither can they e.g. take a photo of the screen or read a QR code displayed on the screen with some other device, which is something an app might need to query for.

Question to the CSSWG is: should we add a media query for this device limitation, and if so, what should it be called?

Start by reviewing the issue's discussion of the existing hover, pointer, and environment-blending media queries. Determine whether enclosed screens require a new query and what its name and semantics should be; done means the CSS Working Group has reached a direction on the proposal.