crrdlx on Nostr: Looks amazing. What am I looking at exactly though? Is this a nostr client? A web ...

Looks amazing. What am I looking at exactly though? Is this a nostr client? A web interface that gathers nostr events and presents them in a neat UI?
I love the "books" display. It's like having ebook reader software, such as Calibre. It's been a while since I've used Calibre, but as I recall, the ebook file must be housed on your device. With this, I understand that it's not. Rather, the "book" itself is housed across the nostrverse in separate notes.
Not a lot of time right now, but I'll try to take a deeper look later on.