I spent some time at the agency Level Studios doing work for Apple. My role was to help maintain apple.com. In my time there I did work on the Apple Music and Final Cut portions of the site.
For Apple Music, I was mainly responsible for the slideshow that describes all the ways to interact with Apple Music(at the time) as well as smaller portions here an there on the rest of the page.
With Final Cut, my main responsibilities were the tech specs page but I also helped out as needed on other pages.
Though I believe it’s now changed, at the time, Apple was using an in-house custom framework that constructed pages out of Markdown and merged the output with stand-alone JS and SCSS files that were using in-house libraries to build each part of the site.
Main page that I worked on for the Final Cut section - built the JavaScript and CSS
Also helped a lot with this section of the Apple Music section of the site back in 2017.
https://web.archive.org/web/20171102003157/https://www.apple.com/apple-music/
https://web.archive.org/web/20221122181606/https://www.apple.com/final-cut-pro/specs/