Yaru is the default theme for Ubuntu, backed by the community.
It contains:
* a GNOME Shell theme based on the upstream GNOME shell theme
* a light and dark GTK theme (gtk2 and gtk3) based on the upstream Adwaita
Gtk theme
* an icon & cursor theme, derived from the Unity8 Suru icons and Suru icon
theme
* a sound theme, combining sounds from the WoodenBeaver and Touch-Remix
sound themes.
This package contains GTK+ 3 theme.