Add variations of external link CSS for different font sizes
Add variations of external link CSS for different font sizes

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