Thank you so much! Love your questions.
> How expensive/difficult is it to have each page in different colour? The production was very specific to our design needs. For this edition, each book cost me more than $65 to produce.
> it looked like "product sans" at first glance We have licensed all our fonts which are: ABC White, Affairs and IBM Plex Mono.
> Tell me more about the page quality The paper is Fedrigoni Arena Rough Extra White
> Why didn't you choose flat binding? This question is great! We wanted to have that characteristic curve of opened books. It was very much a thoughtful decision.