GitHub Pages

Jekyll

Whilst ordinarily you would need to generate your site’s HTML using jekyll build then upload it to the web server of your choice, GitHub allows for raw Jekyll projects to be uploaded to its service; it will handle the building and serving of the HTML itself from the Jekyll project.
blog.cloudflare.com/secure-and-fast-github-pages-with-cloudflare

HTTPS

GitHub Pages doesn’t support SSL on GitHub Pages for custom domains!

You can enforce HTTPS to add a layer of encryption for traffic to your GitHub Pages site if it has a github.io domain.
help.github.com/articles/securing-your-github-pages-site-with-https