Mobile-first typography
Mobile-first typography

- Set $font-size-640 and $line-height-640 first
- Override with $font-size and $line-height for larger screens
- Do $is-print check last, to override any font-size set with the print
font size

TFOH/govuk_frontend_toolkit,alphagov/govuk_frontend_toolkit,quis/govuk_frontend_toolkit,TFOH/govuk_frontend_toolkit,TFOH/govuk_frontend_toolkit,TFOH/govuk_frontend_toolkit,alphagov/govuk_frontend_toolkit,quis/govuk_frontend_toolkit,alphagov/govuk_frontend_toolkit,alphagov/govuk_frontend_toolkit,quis/govuk_frontend_toolkit,quis/govuk_frontend_toolkit