Additional customizations for GitHub Pages
You can further customize your GitHub Pages site in many ways.
GitHub Pages is available in public repositories with GitHub Free, and in public and private repositories with GitHub Pro, GitHub Team, GitHub Enterprise Cloud, and GitHub Enterprise Server.
Creating a custom 404 page for your GitHub Pages site
You can display a custom 404 error page when people try to access nonexistent pages on your site.
Using syntax highlighting on GitHub Pages
You can have code snippets highlighted so that they are easier to read on your GitHub Pages site using Rouge, Jekyll's default syntax highlighter.
Using a static site generator other than Jekyll
You can use a static site generator other than Jekyll for your GitHub Pages site by using a different build process.
MIME types on GitHub Pages
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.