I noticed something that I think is incorrect behavior based on my playing of the original. If I have a row that has 2 - 2 - 4, when I press right, it goes straight to 8, rather than the behavior that I think is supposed to happen - press right once and get 4 - 4, press it again and get 8. A minor difference but does actually change the gameplay a bit.
Edit: I’m on this issue, currently trying to write a test to reproduce.
Edit 2: fixed!
Long answer: Over the course of development there had been some thought as to whether or not the Softcover site would just be an informational site for the Softcover gem and a place for authors to get their sales stats, and then each book page would be its own separate thing that would be more or less fully-customizable by the author. Point is that most people would have had to be interacting with the site on a desktop because that's where they'd need to do things like install gems and run the server.
We've kind of moved away from the idea of having a Myspace free-for-all, towards something that is more of a designed garden, planning on allowing a good deal of customization on the book side – each book page loads a completely separate stylesheet from what is used on the rest of the site for that reason.
With that I'm going to be focusing on redoing a lot of the presentation side to meet what we'll need, and a part of that will be responsive styling.
I'm not saying this is inaccessible - it looks like it would be okay at least as far as screen readers are concerned, though there may be color contrast issues depending on the image (here's an idea for a cool project - analyze the image and set a color on the caption that meets WCAG AA contrast ratios). It's just every time I see a some cool new css/js wizardry, the only way I can find out whether there's any accessibility compliance is to poke through the rendered markup, test out hover states, etc.