3421: Fix CSS class on post-to-idp form
3421: Fix CSS class on post-to-idp form

The form should be hidden for all users (with and without JS enabled).

Authors: 2da5894dda447b0d0fb23a746d6472ae6c95499b@lloydnye

alphagov/verify-frontend,alphagov/verify-frontend,alphagov/verify-frontend,alphagov/verify-frontend