Proposal: Allow Web Apps to use OS translucent materials

[diekus]

Hola CSS WG 👋🏽, we've got an idea for...

Materials in Installed Web Applications

"This explainer proposes a way to allow installed web applications to use materials from the underlying platform, to use as the app's window frame background effect. When enabled, and if the platform supports it, the frame of the installed web application will use the specified visual effect, and if the background of the page is transparent the material will be visible."

We've been brainstorming and would like to request feedback on this idea that would allow installed web apps to "use" OS materials like macOS's ultrathin and Windows' Mica (there's a lot more details on how we expect this to be handled on the explainer).

The only kind of related proposal I could find is this one for transparent windows, but it is a completely different scope and use case. The materials proposal aims at allowing installed web apps to access the platform's native look and feel.

Appreciate the discussion.

@diekus and @aluhrs13

[fosple]

Would also be interested in using OS background blur / transparency for PWAs - in order to make them look more native. Especially for MacOS and the new Glass Look, PWAs without transparency look quite dated.