- Open Graph and Twitter card tags in English on index.html and semplice.html
- cover.jpg (1200x630): the light-blue drawing with the title
- so Telegram, X and WhatsApp show title, description and image
- anteprima-2a86b5/index.html: full 15-step version, light-blue, voice IT/EN/ES
- anteprima-2a86b5/semplice.html: simple 8-step version, light-blue, voice IT/EN/ES
- audio clips in voce*/ and voce-det*/ next to the pages
- noindex, not linked from menus or sitemap: preview to share by link only