Ensure that the vertical spacing inside each panel is similar.
This makes the transition between each panel smoother and makes
the control center feel more cohesive.
Settings panels are given 32px above and below their content
and 32px vertical space between major sections. 12px space is
placed below headings.
Bluetooth, displays and printers are not addressed.
https://bugzilla.gnome.org/show_bug.cgi?id=786384
Make it possible for panels to go all the way to the edge of the
shell. This is particularly important for panels that scroll, such
as the new power panel. All other panels are changed to compensate
for the loss of external padding.
https://bugzilla.gnome.org/show_bug.cgi?id=691229
