Update Design to follow new Libadwaita

[mbeps]

Prerequisites

• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.

Checklist to make sure the issue is not on your end

• I have made sure that I do not have multiple versions of the theme installed. Only one version should be installed in either ~/.local/share/themes or /usr/share/themes or ~/.themes
• The file ~/.config/gtk-3.0/gtk.css does not exist. (If it does, backup and remove it.)
• I have logged out and in again.
• Dark theme only. I have enabled adw-gtk3-dark in gnome-tweaks AND set the appearance to dark in gnome-control-center
• The flatpak theme is installed org.gtk.Gtk3theme.adw-gtk3 and org.gtk.Gtk3theme.adw-gtk3-dark
• The app I'm having an issue with is an actual GTK3 app and is not coded using another toolkit like GTK2, GTK4, QT, etc.
• I have created a new user profile without any modifications except adw-gtk3.

Description

The new Libadwaita has a new design for the sidebar. The sidebar and the rest off the app container are separate. The theme needs to e updated to follow the new Libadwaita design.

New design

OS and version [e.g Fedora 37]

Fedora 39

Adw-gtk3 version. Also specify your installation source. [e.g tar.xz, AUR, git main branch]

4.9 from Fedora Copr

GNOME version

45

Application name and version (If the issue is with an app.)

No response

[lassekongo83]

The sidebar can't be expanded into the headerbar on GTK3. Other than that I've already started some minor work that probably will be finished sometime after Arch gets GNOME 45.