[web] [fix] align unread buttons

Summary: there isn't a design for unread button, but I'd assume we would want to align the buttons across the board.

Test Plan: make sure buttons are aligned. (three dot vertical buttons)

Reviewers: atul, def-au1t, palys-swm

Reviewed By: palys-swm

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

Differential Revision: https://phabricator.ashoat.com/D3441