File system errors

Something about
~/.config/gtk-3.0/gtk.css
came up

Theme parsing error: gtk.css:--after installing code-oss

Compare
~/.config/gtk-3.0/gtk.css
with
/etc/skel/.config/gtk-3.0/gtk.css
(where this file originates when the user account is created)

is what I’d do

There seems to be a syntax error in ~/.config/gtk-3.0/gtk.css