This is the desktop version of T225535 (my understanding is that the work needs to be done separately).
User story: As a user, I'd like a clearer read-state for notifications, so that it's more obvious which notifications have been read.
Changes to "read" treatment:
- update background to Base90 (#f8f9fa)
- change icon color to Base20 (#54595d)
- change primary text to Base30 (#72777d)
- change secondary text to Base50 (#a2a9b1)
- update dot indicator to white background with blue outline (#36c) – *note, the expectation is that this change will carryover to mobile
- add subtle shadows to the header and footer of the tray (OOUI reference)