fix centering issue hero text

Summary: Center hero text with phone on resize

Test Plan:
resize the window
Before: https://share.getcloudapp.com/Kou7e8D0
After: https://share.getcloudapp.com/04u5gnoG

Reviewers: palys-swm, ashoat, atul

Reviewed By: ashoat

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

Differential Revision: https://phabricator.ashoat.com/D2269