The slides!
These slides are built using remarkjs, which allows you to write your slides in nice simple markdown and turns them into beautiful, browser-powered slides complete with speaker notes. Read its readme to find out more about it.
This particular project uses yarn and whatnot to give some niceties in the development environment that probably aren't necessary. The only thing you actually need are the files in the public folder--you could just open index.html in a browser, and BAM! Slides!
I'm pretty proud of the styles I used for the slides. It took me a while to figure out how to override RemarkJS's styles in that way. If you enjoy it, feel free to copy it.