Notification area (systray) icons shadow

im trying to add shadows to tray icons , i can add shadows to pulseaudio and power button as seen in this picture

but i can’t add shadow to notification area (status tray plugin) icons
what i’ve tried so far :
added this to /home/mohamed/.config/gtk-3.0/gtk.css

-gtk-icon-shadow: -1px -1px 2 #000, 1px -1px 2 #000, -1px 1px 2 #000, 1px 1px 2 #000;

i also used gtk inspector to find the proper object names , there was no buttons registered in the objects , only widgets are registered , and i have tried to add -gtk-icon-shadow to every one of them , didn’t work

best i got so far is to change the box color with gtk-inspector , -gtk-icon-shadow doesn’t work