This is a great concept that I wish I could play more of, but my browser (Firefox) seems to not like the battle phases. Dragging cards into where they go is hellish, and won't work most of the time. I had to repeat the dragging five times to get it to work at times. I would play it more if there was a desktop version.
I enjoy the CYOA concept though I'm not sure if being able to read (since you can) a page that you cannot flip to next to the one you're own is intentional. The ones I found didn't necessarily clue me in on that.
The other thing I really want to comment on is that while it's helpful to always have them there as a reminder, the battle rules menu being the only way you can learn how to fight is definitely not good. There is a lot to it that uses terms that are not properly represented in the battle UI, so it doesn't make for a good visual learning experience, so to say. It took me the entire fight to decipher what was going on, and even then it felt like my actions didn't really seem that meaningful - I'd assume this is alleviated once you get more cards and are able to fight faster, but this time around that was just not possible for me.
I'm looking forward to future updates!