The SSO-only login doesn't fit GnLoginCard's username/password form (the
adapter always renders both fields), so the escape-hatch card is replaced
with the kit's own login-card markup (article.card.login-card + header +
card-content + GnButton) — the same contract kit.css ships for
GnLoginCard, minus the form. Custom card border/title/subtitle styles are
gone; overlay keeps positioning only.