[web] [fix] fix unread last message timestamp
Summary:
size and padding didn't match figma.
after:
before:
Test Plan:
it should match figma
https://www.figma.com/file/a1nkbWgbgjRlrOY9LVurTz/Comm-%2F-Desktop-app?node-id=1170%3A79583
Reviewers: atul, def-au1t, palys-swm
Reviewed By: palys-swm
Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga, yayabosh
Differential Revision: https://phabricator.ashoat.com/D3725