By "pixel accurate", do you mean the user interface or the rendering? Is she able to leverage the HTML 2D Canvas API or does she have to go lower level than that?
I’ve gone on a lot of rabbit holes digging into original source code and dev manuals for this project, hopefully one day I’ll write some of it up somewhere. I think what’s been interesting is iterating towards the most elegant solutions has often meant ending up with pretty similar approaches to what Atkinson originally used.