[libadwaita] (9 commits) Non-fast-forward update to branch wip/exalm/background-colors

[Alexander Mikhaylenko <alexm src gnome org>]

The branch 'wip/exalm/background-colors' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  a9c306f... stylesheet: Apply headerbar border opacity separately
  140b825... stylesheet: Explicitly reset flat header bar color
  3551a3a... tmp

Commits added to the branch:

  ad0c843... stylesheet: Apply headerbar border opacity separately
  688ea0f... stylesheet: Explicitly reset flat header bar color
  fa2bcff... stylesheet: Derive menubar separator color from text
  84bc5f6... Rework .content list style
  c67fddc... stylesheet: Remove notebook tab.reorderable-page style
  b32f750... stylesheet: Use currentColor for notebook tab hover
  60b8c78... stylesheet: Stop using scss functions for tab bar styles
  aea5603... stylesheet: Stop using scss functions for treeview styles
  1591d4b... a