How to add blurred background to gnome-shell using gnome-shell.css?

[mazharhussain]

I am the developer of Login Manager Settings and I want my application to be able to set blurred background for GDM.

It can change GDM background by modifying gnome-shell.css found in gnome-shell-theme.gresource

I tried adding

filter: blur(8px);

to gnome-shell.css, it didn’t work. Is there any way to do this that I don’t know?

What program does gnome-shell use to parse its CSS?

Also, I know I can use ImageMagick to modify the image directly but ImageMagick is slow and I would prefer not to use it.

[fmuellner (Florian Müllner)]

@mazharhussain

Is there any way to do this that I don’t know?

No. It is not possible to add a blur effect via CSS.

[ntd (Nicola Fontana)]

@mazharhussain

What program does gnome-shell use to parse its CSS?

I suppose it is using the internal CSS parser that GTK provides:
https://docs.gtk.org/gtk3/css-overview.html

[ebassi (Emmanuele Bassi)]

No, the Shell has its own CSS parser and style machinery.