[progers7]

This was recently implemented in Chromium-based browsers (M76) too. https://web.dev/backdrop-filter has some more information about the CSS, and https://www.chromestatus.com/feature/5679432723333120 has more information about the implementation.

[heycam]

And this is landing very soon in Firefox, behind a pref. https://twitter.com/svoisen/status/1159322370122768384

[frosted-panel]

As of yet, the browser support for this is very shoddy. Not to mention outdated/legacy browsers like IE.