Revert "[web] [darkmode] unread button"

Summary: This reverts commit fb93ae4b58bab7a9c48a983fee2f9e98a74b1b8e.

Test Plan:
this commit is breaking master. Styling is incorrect.

I should have waited for this diff: https://phabricator.ashoat.com/D3180 to land first.

Reviewers: atul, ashoat

Reviewed By: ashoat

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3204