I used to do this sort of thing by hand[1], and I can tell you it's very tedious (and didn't look this good).
1: https://docs.google.com/presentation/d/1KVMwffTe-aam8Mq7LwfZ... (look at animations or in presenter view starting about slide 6)
Would be nice if arrow and/or spacebar worked for scrolling on this website. They appear to have been sacrificed to the god of parallax.
edit: they work until you click something.
I used to do this sort of thing by hand[1], and I can tell you it's very tedious (and didn't look this good).
1: https://docs.google.com/presentation/d/1KVMwffTe-aam8Mq7LwfZ... (look at animations or in presenter view starting about slide 6)