You can use this in initial-setup.json:
"stylesheetName": "gdm3.css"
This is what we use in Pop, in order to use the same theme as gdm3. That theme may be changed by alternatives, and is already a link to ubuntu.css on Ubuntu.
You can use this in initial-setup.json:
"stylesheetName": "gdm3.css"
This is what we use in Pop, in order to use the same theme as gdm3. That theme may be changed by alternatives, and is already a link to ubuntu.css on Ubuntu.