Make textboxes auto expand later
Make textboxes auto expand later

At two lines the subject textbox was expanding even when it was empty.
This commit makes the distance at which textboxes start expanding less
sensitive.

alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin