Use Adapta theme for Lock Screen

I have installed the Adapta theme.

I successfully enabled the Adapta Nokto them on the GDM3 Login Screen using:

sudo update-alternatives --install /usr/share/gnome-shell/theme/gdm3.css gdm3.css /usr/share/themes/Adapta-Nokto/gnome-shell/gdm3-Adapta-Nokto.css 1
sudo update-alternatives --config gdm3.css

This, of course, shows the Adapta Nokto theme whenever I need to log into my system.

However, if I lock my screen, the default gnome-shell theme is shown (/usr/share/gnome-shell/theme/gnome-shell.css).

How can I make the Lock Screen use the Adapta-Nokto theme (/usr/share/themes/Adapta-Nokto/gnome-shell/gdm3-Adapta-Nokto.css)?

Note: My system desktop theme is set to Adapta, and my gnome-shell theme (top bar and dock) is is set to Adapta-Nokto (because I am using the User Themes extenson).

The solution is to use the gnome-shell-theme.gresource file from the Adapta-Nokto theme.

EDIT: I updated this solution to create a link to the Adapta-Nokto gnome-shell-theme.gresource theme file, instead of copying it. This way, the Lock screen will always use the most recent version of the Adapta-Nokto theme, whenever it is updated.

1. Open a terminal, and change to the gnome-shell directory.

   cd /usr/share/gnome-shell/
   

2. Backup the original gnome-shell-theme.gresource file. The following command will only create the backup, if the current file is not a link (created using step 3).

   if ! [[ -h gnome-shell-theme.gresource ]]; then sudo mv gnome-shell-theme.gresource gnome-shell-theme.gresource.original; fi
   

3. Link to the Adapta-Nokto theme's gnome-shell-theme.gresource file.

   sudo ln -frs /usr/share/themes/Adapta-Nokto/gnome-shell/gnome-shell-theme.gresource gnome-shell-theme.gresource
   

4. Reboot to enable the new Lock screen. (Just loging-out and logging-back-in is not sufficient to enable the new Lock screen, because you are repeatedly taken back to the Login screen after you enter your password).

5. Note: if the gnome-shell-common package is updated at a future time, you may need to execute steps 1 thru 3 again to re-enable the Adapta-Nokto Lock screen theme.

Reference: Materia GDM Theme