https://yagmin.com/blog/ https://github.com/yagmin/
Creator here - this was much more technically difficult than it seems, because rendering pixel perfect backgrounds with scaling width is non-obvious. Hit 'Esc' and you can set some options, including changing the background pattern.
If you want to see a big file, I have a direct link to load the Blocktronics WTF4 ANSI which is over 4000 lines: https://sure.is/ansi/?wtf4=1
This project is an enhanced reader for Ycombinator Hacker News: https://news.ycombinator.com/.
The interface also allow to comment, post and interact with the original HN platform. Credentials are stored locally and are never sent to any server, you can check the source code here: https://github.com/GabrielePicco/hacker-news-rich.
For suggestions and features requests you can write me here: gabrielepicco.github.io