[renumber-windows][1]:
> If on, when a window is closed in a session, automatically renumber
> the other windows in numerical order. This respects the base-index
> option if it has been set. If off, do not renumber the windows.
[1]: tmux(1)
Instead of putting the window id and name in filled rounded "boxes" with
the help of Unicode characters, display simply the text on neutral
background and change only the foreground. This makes the status line
more minimal while also "supporting" terminals without a patched
Nerd-font.