Light Blog is a light and responsive Jekyll theme, and it's easy to be used as a remote theme.
Github Pages' remote theme is kind like a gem-based theme. The user doesn't need to worry about the theme files (like HTML, CSS, etc.), but focus on the posts. When the theme is separated with your content, it's easier to deployed and update your site.
With gem-based themes, some of the site’s directories (such as the
_sassdirectories) are stored in the theme’s gem, hidden from your immediate view. Yet all of the necessary directories will be read and processed during Jekyll’s build process.
Check out the post for more info on how to use this theme in your site.
The theme is available as open source under the terms of the MIT License.