High Contrast Installer

Hi all,

The wiki page "Base system accessibility wishlist" [0] has "Check the
installer text and background colors provide enough contrast (including as
shades of grey) and or offer options to change them.".

bsddialog provides already a black and white theme.
Default theme:
$ bsddialog --yesno "Default Theme" 0 0
Black and White theme:
$ bsddialog --theme blackwhite --yesno "Black and White Theme" 0 0

Does it provide enough contrast? Suggestion and Ideas? I can update it or
create a new theme.

[0] https://wiki.freebsd.org/Accessibility/Wishlist/Base

Best Regards,
Alfonso