How to expand ScrollView widget?

Hello!
I use grid layout and when using placeholder they expanded all space. But when I use ScrollView (Panel) it takes minimum space. How to expand it?

    # Grid for settings
    grid = await self.view.dock_grid(edge="left", name="left")

    grid.add_column(fraction=1, name="left")
    grid.add_column(fraction=1, name="center")
    grid.add_column(fraction=1, name="right")

    grid.add_row(fraction=10, name="top", min_size=2)
    grid.add_row(fraction=10, name="middle")
    grid.add_row(fraction=1, name="bottom", min_size=3)

    grid.add_areas(
        text="left,top-start|middle-end",
        area2="center,top-start|middle-end",
        area3="right,top-start|middle-end",
        area_rasa_url="left,bottom",
        area_connector="center,bottom",
        area_sender="right,bottom",
    )

    grid.place(
        text=self.output,
        area2=Placeholder(name="area2"),
        area3=Placeholder(name="area3"),
        area_rasa_url=self.rasa_url,
        area_connector=self.connector,
        area_sender=self.sender,
    )

I mean the output widget that is

   self.output = ScrollView(
        contents=Panel(
            "",
            # Align.center(Pretty(self, no_wrap=True, overflow="ellipsis"), vertical="middle"),
            title="Report",
            border_style="blue",
            box=rich.box.SQUARE,
            height=30
            # style=Reactive(""),
            # height=Reactive(None),
        )
    )