HighContrast: rework high contast theme
HighContrast: rework high contast theme

Make it as decent as the GTK2 theme. Inverse variant to follow.

Distrotech/gnome-themes-standard,cosimoc/gnome-themes-standard,DoctorJellyface/gnome-themes-standard,Distrotech/gnome-themes-standard,ChrisCummins/gnome-themes-standard,rgcjonas/adwaita-semidark,magcius/gnome-themes-standard,cosimoc/gnome-themes-standard,ChrisCummins/gnome-themes-standard,cosimoc/gnome-themes-standard,rgcjonas/adwaita-semidark,magcius/gnome-themes-standard,cosimoc/gnome-themes-standard,DoctorJellyface/gnome-themes-standard,rgcjonas/adwaita-semidark,ChrisCummins/gnome-themes-standard,rgcjonas/adwaita-semidark,ChrisCummins/gnome-themes-standard,magcius/gnome-themes-standard,ChrisCummins/gnome-themes-standard