It doesn't seem HTML-first though. Also the Github description says it's a library of web components, this may be misleading because this project doesn't use Web Components.
I wasn't expecting it to use Web Components, I guess that's what happens when you give something a generic name. Similarly if some company named a code editor Code.
It's supposed to be named Visual Studio Code, VS Code for short, but I think Microsoft has started using just "Code" for things like the title of its Mac app bundle, which has gotten confusing/annoying.
