I got pretty far, did all the design. I wanted to run a client side simulation in javascript though, and found I needed to host a local server as chrome refused to read modules from a file due to CORS permissions (running chrome with the usual arguments didn't fix it).
At this point, since I needed an outside piece of software to run things anyway, I figured I might as well switch to webpack dev-server and get the whole modern frontend ecosystem. I then quickly started replacing my home grown dom syncing with vuejs, and snowballed from there.
I definitely learned a couple things, so time well spent, but I'm also going straight to webpack next time. I know it'll only take a few hours before I start hitting the limits of what vanilla js can do, and while reinventing the wheel was fun and educational, it didn't result in a better wheel.