call: Adjust the preview rectangle colors
call: Adjust the preview rectangle colors

As our default background is now black the non-highlighted previews
get hard to see. Change the rectangle colors to white for the
highlighted version and a darkened white for the non-highlighted.

Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets