When building applications that display untrusted content, security designers have a major problem— if an attacker has full control of a block of pixels, he can make those pixels look like anything…
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.