I'm using Firefox, but also I'm on OSX which might be likely the cause if no one else is experencing it! I've attached an example of how it looks. The display view isn't small or anything, and I can see it's meant to look a lot sharper in the screen shots
Ah. I figured it out. CSS property `image-rendering` must be set to `crisp-edges` in order for firefox to render it properly. Thanks for pointing this out! I updated the game so now it should render properly on firefox as well.