Lock Screen Shell Not in Dark Mode / Specific Theme

I notice that my shell on my lock screen wasn't the same theme was when I'm logged into my user. I was wondering if that is changeable into a dark mode or even a specific shell theme that I have downloaded.

Things I've tried to change to dark mode:

Edit the stylesheet in /usr/share/gnome-shell/modes/ubuntu.json from

{
    "parentMode": "user",
    "stylesheetName": "Yaru/gnome-shell.css",
    "themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",
    "debugFlags": ["backtrace-crashes-all"],
    "enabledExtensions": ["", "", "desktop-icons@csoriano"]
}

to

{
    "parentMode": "user",
    "stylesheetName": "Yaru-dark/gnome-shell.css",
    "themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",
    "debugFlags": ["backtrace-crashes-all"],
    "enabledExtensions": ["", "", "desktop-icons@csoriano"]
}

However, this didn't work.

Thanks a lot!