make Gtk window transparent using css

i m using python.
How to make Gtk window tranparent using css?
for instance

*{       background-color:transparent;       opacity: 0.9;  }  

this makes all the labels in the window tranparent but window itself is not tranparent. how do i achive this ?

https://stackoverflow.com/questions/66979034/make-gtk-window-transparent-using-css April 07, 2021 at 11:05AM