zen-browser/desktop ? reverse-engineered prompt

I want to build a desktop web browser focused on providing a calmer, more productive internet experience. The whole point is to create a 'zen' feeling for the user, so the interface should be minimalist, clean, and free of distractions.

Let's base it on Firefox, using its underlying engine, but create a completely new and simplified front-end. It should work on the major desktop platforms. The main goal isn't just to clone a browser, but to really nail that feeling of focus and calm. For the tech stack, let's use JavaScript and whatever else makes sense for building a custom browser on top of Firefox. Feel free to look up the current best practices for doing that.