The frontend was Ruby?? Are you sure?

Not literally. And I would hardly say it was a matter of language superiority. I love Ruby myself. But Github was a lot simpler when it was still just a Rails app.

But Rails was SSR by default, and most of the frontend was just Embedded Ruby (ERB) template files all over the place. And way back when, it was even relatively common to use Javascript supersets like CoffeeScript[1] and Opal[2]. The latter being Ruby that compiled to JS.

[1]: https://coffeescript.org/ [2]: https://opalrb.com/

Yes, standard rails. Rails does not ship with components out of the box and the most prominent component system for rails was built and is maintained by GitHub. They have been moving to React for the last few years though, it seems to be more about hiring and ergonomics rather than capability.

As in rendered server-side.