Also install Extension Manager from Flathub to manage these
# Fedora (dnf)
sudo dnf install gnome-tweaks
# Ubuntu (apt)
sudo apt install gnome-tweaks
Refer the adw-gtk3 repo
# Fedora (dnf)
sudo dnf install adw-gtk3-theme
# Ubuntu (apt)
curl -s https://julianfairfax.codeberg.page/package-repo/pub.gpg | gpg --dearmor | sudo dd of=/usr/share/keyrings/julians-package-repo.gpg
echo 'deb [ signed-by=/usr/share/keyrings/julians-package-repo.gpg ] https://julianfairfax.codeberg.page/package-repo/debs packages main' | sudo tee /etc/apt/sources.list.d/julians-package-repo.list
Now set the them for Legacy applications to Adw-gtk3-dark
under Appearance
section in the Tweaks
app
Visit gnome-look.org to browse system themes, icon-packs, cursors, GRUB themes etc. (might have to debug to get it working)