The current GDM should be including colors from the gtkrc within the theme itself (ie the dark colors, which are included in /usr/share/gdm/themes/Human/gtk-2.0/gtkrc).
The current GDM should be including colors from the gtkrc within the theme itself (ie the dark colors, which are included in /usr/share/ gdm/themes/ Human/gtk- 2.0/gtkrc) .