The activities button doesn't have an icon, which makes its horizontal
padding appear a bit smaller than the padding of most other items in the
panel.
We're going to indicate hover and focus of items in the panel using a
pill-shaped background color, which means the padding of those items
will get more visible. So give the activities button a special treatment
and slightly increase its padding to make sure the new indicator will
look good.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1397>
Now that the screen shield is gone (at least, as it used to
be), the corresponding session mode is not necessary anymore
as well.
Remove the 'lock-screen' session mode, and the corresponding
CSS.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/872
- panel fg color was derived from bg color. Not a good idea as it's not
just light/drk, but HC as well.
- deriving from dark theme means contrast for things like popover items
is better.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/904
