Sway tabbed layout
Sway has an interesting feature called "tabbed layout". In this layout, windows are organized with tabs as you would do in a browser window. The difference is that it works universally for all apps, even those that don't have native tab support.
I liked it so much, that I'm looking for a way to remove all window decorations from my browser: tabs, panels, url bar etc. And use what my window manager provides out of the box.
I know there is Surf, but it only supports X11, and is not very secure. Then, there is Vivaldi that uses Chromium and has the ability to hide almost everything. What turns me off is that its extensions are closed source.
What I'll be experimenting with next is what's called userChrome.css, which allows you to tune Firefox interface. Let's see if I can make it behave the way I want.