fix: align synced site fragments with static layout

[vitormattos]

Summary

• align the synced header fragment desktop layout with the static site navigation structure
• harden fragment CSS specificity so WordPress theme styles do not override CTA and footer presentation
• fix footer grid sizing and desktop breakpoint behavior for the synced fragments

Testing

• docker compose exec php bash -lc "npm run build-assets"
• compared the static site header/footer layout with the synced fragment harness during validation