Maybe I missed it, but why are you embedding a zipfile of gzip streams rather than just embedding the static site's files with an `embed.FS` and serving from that?
Aside — the architecture diagrams on https://xeiaso.net/blog/xesite-v4/ are not displaying in-browser for me, but do transfer correctly and are viewable on my computer. Maybe another mime issue, as the network inspector shows them being transferred with type "octet-stream"?
Repro by visiting the URL in latest Firefox, Safari, or Chrome.