Yeah, the zoom definitely changes the experience. I tried to strike a good balance between the layout being big enough to read somewhat comfortably, while small enough to see the overall "newspapery" layout, and 1200px wide by default is what I ended up settling on. Of course users I think can zoom in and out on their own if they prefer another size, like you did.
The implementation is buggy though. Trying to zoom in on iOS Safari reshuffles the content around and keeps it at its original size. It might be fine on desktop