You can further customize your GitHub Pages site in many ways.
You can display a custom 404 error page when people try to access nonexistent pages on your site.
GitHub Pages supports more than 750 MIME types across 1,000s of file extensions. The list of supported MIME types is generated from the mime-db project, which aggregates MIME types from the Apache and Nginx projects as well as the official IANA list of internet content types.
You can use a static site generator other than Jekyll for your GitHub Pages site by using a different build process.