Improve the readability of the rdetail_extras headers in TTPAC

Improve the readability of the rdetail_extras headers in TTPAC

The previous version included green text, on a light green background, which
was very difficult to read, especially for visually impaired patrons.
This commit serves to change the header background to a darker green, along
with a high contrast white text.

Signed-off-by: Michael Peters <mrpeters@library.in.gov>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>
Signed-off-by: Dan Wells <dbw2@calvin.edu>