URL: https://github.com/shimmerproject/Greybird

Copyright 2009–2019 Simon Steinbeiß, Satyajit Sahoo, Pasi Lallinaho, Carson Black, Maurizio Galli

Greybird is dual-licensed as GPLv2 or later and CC-BY-SA 3.0 or later.

Greybird is the default theme in Xubuntu 11.04 onwards.

The Greybird desktop suite includes:

• Gtk+2 theme
• Gtk+3 theme
• Xfwm4 themes (normal and compact)
• xfce-notifyd theme (dark and bright)
• Emerald theme
• Metacity theme
• Mutter theme
• Gnome Shell theme
• Plank theme
• Unity support

Dependencies for Gtk+2 support:

• gtk2-engines-murrine (>= 0.90)

The Gtk+3 theme uses the builtin engine and consequently has no dependencies.

Debian or Ubuntu:

sudo apt install autoconf libgdk-pixbuf2.0-dev libglib2.0-bin librsvg2-dev meson ruby-sass sassc

Fedora:

dnf install gdk-pixbuf2-devel librsvg2-devel meson rubygem-sass

openSUSE:

zypper in fdupes gdk-pixbuf-devel gdk-pixbuf-loader-rsvg glib2-devel meson sassc

meson --prefix=$HOME/.local builddir
cd builddir
ninja
ninja install
ln -sf ~/.local/share/themes ~/.themes # Required for GTK2

meson --prefix=/usr builddir
cd builddir
ninja
ninja install

You don't need to use sudo anywhere in the build and install process, as Ninja will elevate with polkit when needed.