siva-flat-themes (GTK2|GTK3 themes).

Siva Flat Themes for gtk3, gtk2, metacity, unity, xfwm4, openbox and
emerald. There are 8 themes included.

Requirements for gtk3 theme: gnome-themes-standard and gtk-engine-unico.
Requirements for gtk2 theme: gtk-engines and gtk-engine-murrine.

Optional dependencies: gtk-engines, murrine, gtk-engines-unico.