This is a nifty visualizer, I'm going to show it to my daughter who I've been teaching programming. We haven't broached registers and general CPU design yet, but this has inspired me to do so! It's interesting that the example shows overflow, but doesn't show the flags register. I'm not a web dev generally, but I think I may fork this one to show it as it exists in the emulator, it's just not rendered.
As promised flags are now visualized.