No browser stuff and Node.js is running in an isolated process. CSS is simply the "language" in which you define the looks of the editor and has nothing to do with web browsers or html.
Are you the author of Kod (that's what some of your comments suggest)? If yes, do you have a roadmap? Do you want to make it open source? I would be pretty excited to try it, out even if it was in scary-alpha state.