[8/n] [landing] remove legal styles in header

Summary: remove legal styling, we spoke about a possible solution during design review to the legal copy pages

Test Plan: header should no longer shift when going to a legal page.

Reviewers: atul, ashoat

Reviewed By: atul, ashoat

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

Differential Revision: https://phabricator.ashoat.com/D2558