Interstellar_1

I use niri since it solves the issues of positioning that you have with stacking window managers and the amount of organization needed for a tiling window manager. I can add many related windows to the same row and use super+the horizontal scroll on my mouse to scroll between windows, and the normal scroll to scroll between workspaces. I have common apps and shortcuts bound to hotkeys, but I prefer a mainly mouse-driven workflow so for everything else I am just dragging things around.

In my browser I have a collapsed left sidebar for tabs and a collapsed top bar for navigation which I can hover to reveal, so all I see by default is the webpage.

What is the separate system?

This looks entirely identical to freetube