What do you do when a website doesn't actually exist? That is essentially the situation with atgreen.github.io. Right now, this GitHub Pages subdomain serves a standard 404 page — there is no content, no business, no blog, and nothing to evaluate. The domain has no archived history in the Wayback Machine, and the WHOIS lookup failed, so we cannot even say who registered it or when.
For context, most personal blogs or small projects hosted on GitHub Pages have at least some content, a contact method, or a social media link. This site has none of those. It is not that there are red flags pointing to a scam; it is that there is no evidence the site was ever functional. The technical infrastructure (TLS, CDN) works fine, but that is like a locked storefront with an empty building behind it.
If you came across this URL from a link or an ad, be cautious — there is no way to verify what the site was supposed to be or who put it there. Without a working page, an owner, or any history, the safest assumption is to avoid it entirely.