I changed the gnome shell theme of the login screen to Yaru-dark by following instructions in this answer. I did notice the dark calendar and system menu when I log on after reboot. However, when I lock my computer with Super+L, the lock screen still has white calendar and system menu, so I would like to make those dark as well.
All the answers I've seen so far are for Ubuntu 18.04, since they refer to /usr/share/gnome-shell/ubuntu.css which I do not have. I do have a /usr/share/gnome-shell/gnome-shell-theme.gresource, but changing that to my dark theme gresource still results in light shell on lock screen. Some other answers refer to a /usr/share/gnome-shell/theme/gdm3.css, which I do not have either (the only css file I see in that directory is a gnome-classic.css).
I would just like to know which css file or which gresource file controls the lock screen theme on Ubuntu 20.04.

