[landing] Text styling

Summary: Styling text based on values specified in "largest" breakpoint of Figma doc. Will consider differences at each breakpoint in later diffs.

Test Plan: NA, everything seems to look as it should on Safari/Chrome/Firefox so far

Reviewers: ashoat

Reviewed By: ashoat

Subscribers: KatPo, palys-swm, Adrian

Differential Revision: https://phabricator.ashoat.com/D1032