>Also, somehow this page completely messed up my browser history - I could not just click the back arrow to navigate back.
It seems like the page updates the page url every time you scroll to a new section, which means you end up with 10+ history entries for the page if you scroll all the way through. To exit out of the page you'd have to click back 10+ times to go through those history entries. Google maps does something similar, where it adds a new entry to history every time you pan, which means your history is polluted with entries for google maps.
No this does it worse, try actually backing out through it after scrolling down, when I tried it went back to the beginning of the current section but then I couldn't get any further back than that so it's adding more entries each time you go back.
It seems like the page updates the page url every time you scroll to a new section, which means you end up with 10+ history entries for the page if you scroll all the way through. To exit out of the page you'd have to click back 10+ times to go through those history entries. Google maps does something similar, where it adds a new entry to history every time you pan, which means your history is polluted with entries for google maps.