I found a multipart/signed message and verified that indeed the "blue" button created by way of notmuch-crypto-part-header is unreadable on dark backgrounds.
Subject: [PATCH v2] emacs: make faces clear on dark backgrounds.
Date: Thu, 20 Oct 2016 11:22:33 -0700
Cc:
From: Matt Armstrong
I found a multipart/signed message and verified that indeed the "blue" button created by way of notmuch-crypto-part-header is unreadable on dark backgrounds.