[web] [fix] dot alignment

Summary:
dot wasn't aligned with color splotch

Test Plan: send a new message, un read dot should be aligned

Reviewers: atul, def-au1t, yayabosh, palys-swm

Reviewed By: palys-swm

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

Differential Revision: https://phabricator.ashoat.com/D3723