gnome-themes-extra-data - 3.28-2 main

This package contains the common architecture-independent files for
Adwaita, the standard GNOME theme, for the GTK 2 toolkit. The GTK 3
equivalent is already included in libgtk-3-0.
.
This package also makes the dark variant of Adwaita available for GTK
3 as a separate Adwaita-dark theme. In newer versions of GTK 3, this
has been superseded by the ability for a single theme to provide both
light and dark variants, which can be selected in the Appearance panel
of GNOME's Settings application (gnome-control-center).