prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Grid cell margin issue
  Adding margin: 1 to the cells within this grid causes unexpected output:
  
  <img width="752" alt="image" src="https://user-images.githubusercontent.com/5740731/190180955-3b10bd1f-60ca-4fda-9473-bc7d9a325b9d.png">
  
  ## `grid_buttons.py`
  
  ```python
  from textual.app import App, ComposeResult
  from textual.widgets import Button
  
  
  class GridButtons(App):
      def compose(self) -> ComposeResult:
          yield Button.success("A")
          yield Button.success("B")
          yield Button.success("C")
          yield Button.success("D")
          yield Button.success("E")
          yield Button.success("F")
  
  
  app = GridButtons(css_path="grid_buttons.css")
  if __name__ == '__main__':
      app.run()
  ```
  
  ## `grid_buttons.css`
  
  ```scss
  Screen {
      layout: grid;
      grid-size: 3;
      grid-rows: 1fr;
      grid-columns: 1fr;
  }
  
  Button {
      margin: 1;
  }
  ```
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `src/textual/layouts/grid.py`
  Content:
  ```
  1 from __future__ import annotations
  2 
  3 from fractions import Fraction
  4 from typing import TYPE_CHECKING, Iterable
  5 
  6 from .._layout import ArrangeResult, Layout, WidgetPlacement
  7 from .._resolve import resolve
  8 from ..css.scalar import Scalar
  9 from ..geometry import Region, Size, Spacing
  10 
  11 if TYPE_CHECKING:
  12     from ..widget import Widget
  13 
  14 
  15 class GridLayout(Layout):
  16     """Used to layout Widgets in to a grid."""
  17 
  18     name = "grid"
  19 
  20     def arrange(
  21         self, parent: Widget, children: list[Widget], size: Size
  22     ) -> ArrangeResult:
  23         styles = parent.styles
  24         row_scalars = styles.grid_rows or [Scalar.parse("1fr")]
  25         column_scalars = styles.grid_columns or [Scalar.parse("1fr")]
  26         gutter_horizontal = styles.grid_gutter_horizontal
  27         gutter_vertical = styles.grid_gutter_vertical
  28         table_size_columns = max(1, styles.grid_size_columns)
  29         table_size_rows = styles.grid_size_rows
  30         viewport = parent.screen.size
  31 
  32         def cell_coords(column_count: int) -> Iterable[tuple[int, int]]:
  33             """Iterate over table coordinates ad infinitum.
  34 
  35             Args:
  36                 column_count (int): Number of columns
  37 
  38             """
  39             row = 0
  40             while True:
  41                 for column in range(column_count):
  42                     yield (column, row)
  43                 row += 1
  44 
  45         def widget_coords(
  46             column_start: int, row_start: int, columns: int, rows: int
  47         ) -> set[tuple[int, int]]:
  48             """Get coords occupied by a cell.
  49 
  50             Args:
  51                 column_start (int): Start column.
  52                 row_start (int): Start_row.
  53                 columns (int): Number of columns.
  54                 rows (int): Number of rows.
  55 
  56             Returns:
  57                 set[tuple[int, int]]: Set of coords.
  58             """
  59             return {
  60                 (column, row)
  61                 for column in range(column_start, column_start + columns)
  62                 for row in range(row_start, row_start + rows)
  63             }
  64 
  65         def repeat_scalars(scalars: Iterable[Scalar], count: int) -> list[Scalar]:
  66             """Repeat an iterable of scalars as many times as required to return
  67             a list of `count` values.
  68 
  69             Args:
  70                 scalars (Iterable[T]): Iterable of values.
  71                 count (int): Number of values to return.
  72 
  73             Returns:
  74                 list[T]: A list of values.
  75             """
  76             limited_values = list(scalars)[:]
  77             while len(limited_values) < count:
  78                 limited_values.extend(scalars)
  79             return limited_values[:count]
  80 
  81         cell_map: dict[tuple[int, int], tuple[Widget, bool]] = {}
  82         cell_size_map: dict[Widget, tuple[int, int, int, int]] = {}
  83 
  84         column_count = table_size_columns
  85         next_coord = iter(cell_coords(column_count)).__next__
  86         cell_coord = (0, 0)
  87         column = row = 0
  88 
  89         for child in children:
  90             child_styles = child.styles
  91             column_span = child_styles.column_span or 1
  92             row_span = child_styles.row_span or 1
  93             # Find a slot where this cell fits
  94             # A cell on a previous row may have a row span
  95             while True:
  96                 column, row = cell_coord
  97                 coords = widget_coords(column, row, column_span, row_span)
  98                 if cell_map.keys().isdisjoint(coords):
  99                     for coord in coords:
  100                         cell_map[coord] = (child, coord == cell_coord)
  101                     cell_size_map[child] = (
  102                         column,
  103                         row,
  104                         column_span - 1,
  105                         row_span - 1,
  106                     )
  107                     break
  108                 else:
  109                     cell_coord = next_coord()
  110                     continue
  111             cell_coord = next_coord()
  112 
  113         # Resolve columns / rows
  114         columns = resolve(
  115             repeat_scalars(column_scalars, table_size_columns),
  116             size.width,
  117             gutter_vertical,
  118             size,
  119             viewport,
  120         )
  121         rows = resolve(
  122             repeat_scalars(
  123                 row_scalars, table_size_rows if table_size_rows else row + 1
  124             ),
  125             size.height,
  126             gutter_horizontal,
  127             size,
  128             viewport,
  129         )
  130 
  131         placements: list[WidgetPlacement] = []
  132         add_placement = placements.append
  133         fraction_unit = Fraction(1)
  134         widgets: list[Widget] = []
  135         add_widget = widgets.append
  136         max_column = len(columns) - 1
  137         max_row = len(rows) - 1
  138         margin = Spacing()
  139         for widget, (column, row, column_span, row_span) in cell_size_map.items():
  140             x = columns[column][0]
  141             if row > max_row:
  142                 break
  143             y = rows[row][0]
  144             x2, cell_width = columns[min(max_column, column + column_span)]
  145             y2, cell_height = rows[min(max_row, row + row_span)]
  146             cell_size = Size(cell_width + x2 - x, cell_height + y2 - y)
  147             width, height, margin = widget._get_box_model(
  148                 cell_size,
  149                 viewport,
  150                 fraction_unit,
  151             )
  152             region = (
  153                 Region(x, y, int(width), int(height))
  154                 .shrink(margin)
  155                 .clip_size(cell_size)
  156             )
  157             add_placement(WidgetPlacement(region, margin, widget))
  158             add_widget(widget)
  159 
  160         return (placements, set(widgets))
  161
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/src/textual/layouts/grid.py b/src/textual/layouts/grid.py
  --- a/src/textual/layouts/grid.py
  +++ b/src/textual/layouts/grid.py
  @@ -150,7 +150,7 @@
                   fraction_unit,
               )
               region = (
  -                Region(x, y, int(width), int(height))
  +                Region(x, y, int(width + margin.width), int(height + margin.height))
                   .shrink(margin)
                   .clip_size(cell_size)
               )
  
verification_info: {"golden_diff": "diff --git a/src/textual/layouts/grid.py b/src/textual/layouts/grid.py\n--- a/src/textual/layouts/grid.py\n+++ b/src/textual/layouts/grid.py\n@@ -150,7 +150,7 @@\n                 fraction_unit,\n             )\n             region = (\n-                Region(x, y, int(width), int(height))\n+                Region(x, y, int(width + margin.width), int(height + margin.height))\n                 .shrink(margin)\n                 .clip_size(cell_size)\n             )\n", "issue": "Grid cell margin issue\nAdding margin: 1 to the cells within this grid causes unexpected output:\r\n\r\n<img width=\"752\" alt=\"image\" src=\"https://user-images.githubusercontent.com/5740731/190180955-3b10bd1f-60ca-4fda-9473-bc7d9a325b9d.png\">\r\n\r\n## `grid_buttons.py`\r\n\r\n```python\r\nfrom textual.app import App, ComposeResult\r\nfrom textual.widgets import Button\r\n\r\n\r\nclass GridButtons(App):\r\n    def compose(self) -> ComposeResult:\r\n        yield Button.success(\"A\")\r\n        yield Button.success(\"B\")\r\n        yield Button.success(\"C\")\r\n        yield Button.success(\"D\")\r\n        yield Button.success(\"E\")\r\n        yield Button.success(\"F\")\r\n\r\n\r\napp = GridButtons(css_path=\"grid_buttons.css\")\r\nif __name__ == '__main__':\r\n    app.run()\r\n```\r\n\r\n## `grid_buttons.css`\r\n\r\n```scss\r\nScreen {\r\n    layout: grid;\r\n    grid-size: 3;\r\n    grid-rows: 1fr;\r\n    grid-columns: 1fr;\r\n}\r\n\r\nButton {\r\n    margin: 1;\r\n}\r\n```\n", "before_files": [{"content": "from __future__ import annotations\n\nfrom fractions import Fraction\nfrom typing import TYPE_CHECKING, Iterable\n\nfrom .._layout import ArrangeResult, Layout, WidgetPlacement\nfrom .._resolve import resolve\nfrom ..css.scalar import Scalar\nfrom ..geometry import Region, Size, Spacing\n\nif TYPE_CHECKING:\n    from ..widget import Widget\n\n\nclass GridLayout(Layout):\n    \"\"\"Used to layout Widgets in to a grid.\"\"\"\n\n    name = \"grid\"\n\n    def arrange(\n        self, parent: Widget, children: list[Widget], size: Size\n    ) -> ArrangeResult:\n        styles = parent.styles\n        row_scalars = styles.grid_rows or [Scalar.parse(\"1fr\")]\n        column_scalars = styles.grid_columns or [Scalar.parse(\"1fr\")]\n        gutter_horizontal = styles.grid_gutter_horizontal\n        gutter_vertical = styles.grid_gutter_vertical\n        table_size_columns = max(1, styles.grid_size_columns)\n        table_size_rows = styles.grid_size_rows\n        viewport = parent.screen.size\n\n        def cell_coords(column_count: int) -> Iterable[tuple[int, int]]:\n            \"\"\"Iterate over table coordinates ad infinitum.\n\n            Args:\n                column_count (int): Number of columns\n\n            \"\"\"\n            row = 0\n            while True:\n                for column in range(column_count):\n                    yield (column, row)\n                row += 1\n\n        def widget_coords(\n            column_start: int, row_start: int, columns: int, rows: int\n        ) -> set[tuple[int, int]]:\n            \"\"\"Get coords occupied by a cell.\n\n            Args:\n                column_start (int): Start column.\n                row_start (int): Start_row.\n                columns (int): Number of columns.\n                rows (int): Number of rows.\n\n            Returns:\n                set[tuple[int, int]]: Set of coords.\n            \"\"\"\n            return {\n                (column, row)\n                for column in range(column_start, column_start + columns)\n                for row in range(row_start, row_start + rows)\n            }\n\n        def repeat_scalars(scalars: Iterable[Scalar], count: int) -> list[Scalar]:\n            \"\"\"Repeat an iterable of scalars as many times as required to return\n            a list of `count` values.\n\n            Args:\n                scalars (Iterable[T]): Iterable of values.\n                count (int): Number of values to return.\n\n            Returns:\n                list[T]: A list of values.\n            \"\"\"\n            limited_values = list(scalars)[:]\n            while len(limited_values) < count:\n                limited_values.extend(scalars)\n            return limited_values[:count]\n\n        cell_map: dict[tuple[int, int], tuple[Widget, bool]] = {}\n        cell_size_map: dict[Widget, tuple[int, int, int, int]] = {}\n\n        column_count = table_size_columns\n        next_coord = iter(cell_coords(column_count)).__next__\n        cell_coord = (0, 0)\n        column = row = 0\n\n        for child in children:\n            child_styles = child.styles\n            column_span = child_styles.column_span or 1\n            row_span = child_styles.row_span or 1\n            # Find a slot where this cell fits\n            # A cell on a previous row may have a row span\n            while True:\n                column, row = cell_coord\n                coords = widget_coords(column, row, column_span, row_span)\n                if cell_map.keys().isdisjoint(coords):\n                    for coord in coords:\n                        cell_map[coord] = (child, coord == cell_coord)\n                    cell_size_map[child] = (\n                        column,\n                        row,\n                        column_span - 1,\n                        row_span - 1,\n                    )\n                    break\n                else:\n                    cell_coord = next_coord()\n                    continue\n            cell_coord = next_coord()\n\n        # Resolve columns / rows\n        columns = resolve(\n            repeat_scalars(column_scalars, table_size_columns),\n            size.width,\n            gutter_vertical,\n            size,\n            viewport,\n        )\n        rows = resolve(\n            repeat_scalars(\n                row_scalars, table_size_rows if table_size_rows else row + 1\n            ),\n            size.height,\n            gutter_horizontal,\n            size,\n            viewport,\n        )\n\n        placements: list[WidgetPlacement] = []\n        add_placement = placements.append\n        fraction_unit = Fraction(1)\n        widgets: list[Widget] = []\n        add_widget = widgets.append\n        max_column = len(columns) - 1\n        max_row = len(rows) - 1\n        margin = Spacing()\n        for widget, (column, row, column_span, row_span) in cell_size_map.items():\n            x = columns[column][0]\n            if row > max_row:\n                break\n            y = rows[row][0]\n            x2, cell_width = columns[min(max_column, column + column_span)]\n            y2, cell_height = rows[min(max_row, row + row_span)]\n            cell_size = Size(cell_width + x2 - x, cell_height + y2 - y)\n            width, height, margin = widget._get_box_model(\n                cell_size,\n                viewport,\n                fraction_unit,\n            )\n            region = (\n                Region(x, y, int(width), int(height))\n                .shrink(margin)\n                .clip_size(cell_size)\n            )\n            add_placement(WidgetPlacement(region, margin, widget))\n            add_widget(widget)\n\n        return (placements, set(widgets))\n", "path": "src/textual/layouts/grid.py"}], "after_files": [{"content": "from __future__ import annotations\n\nfrom fractions import Fraction\nfrom typing import TYPE_CHECKING, Iterable\n\nfrom .._layout import ArrangeResult, Layout, WidgetPlacement\nfrom .._resolve import resolve\nfrom ..css.scalar import Scalar\nfrom ..geometry import Region, Size, Spacing\n\nif TYPE_CHECKING:\n    from ..widget import Widget\n\n\nclass GridLayout(Layout):\n    \"\"\"Used to layout Widgets in to a grid.\"\"\"\n\n    name = \"grid\"\n\n    def arrange(\n        self, parent: Widget, children: list[Widget], size: Size\n    ) -> ArrangeResult:\n        styles = parent.styles\n        row_scalars = styles.grid_rows or [Scalar.parse(\"1fr\")]\n        column_scalars = styles.grid_columns or [Scalar.parse(\"1fr\")]\n        gutter_horizontal = styles.grid_gutter_horizontal\n        gutter_vertical = styles.grid_gutter_vertical\n        table_size_columns = max(1, styles.grid_size_columns)\n        table_size_rows = styles.grid_size_rows\n        viewport = parent.screen.size\n\n        def cell_coords(column_count: int) -> Iterable[tuple[int, int]]:\n            \"\"\"Iterate over table coordinates ad infinitum.\n\n            Args:\n                column_count (int): Number of columns\n\n            \"\"\"\n            row = 0\n            while True:\n                for column in range(column_count):\n                    yield (column, row)\n                row += 1\n\n        def widget_coords(\n            column_start: int, row_start: int, columns: int, rows: int\n        ) -> set[tuple[int, int]]:\n            \"\"\"Get coords occupied by a cell.\n\n            Args:\n                column_start (int): Start column.\n                row_start (int): Start_row.\n                columns (int): Number of columns.\n                rows (int): Number of rows.\n\n            Returns:\n                set[tuple[int, int]]: Set of coords.\n            \"\"\"\n            return {\n                (column, row)\n                for column in range(column_start, column_start + columns)\n                for row in range(row_start, row_start + rows)\n            }\n\n        def repeat_scalars(scalars: Iterable[Scalar], count: int) -> list[Scalar]:\n            \"\"\"Repeat an iterable of scalars as many times as required to return\n            a list of `count` values.\n\n            Args:\n                scalars (Iterable[T]): Iterable of values.\n                count (int): Number of values to return.\n\n            Returns:\n                list[T]: A list of values.\n            \"\"\"\n            limited_values = list(scalars)[:]\n            while len(limited_values) < count:\n                limited_values.extend(scalars)\n            return limited_values[:count]\n\n        cell_map: dict[tuple[int, int], tuple[Widget, bool]] = {}\n        cell_size_map: dict[Widget, tuple[int, int, int, int]] = {}\n\n        column_count = table_size_columns\n        next_coord = iter(cell_coords(column_count)).__next__\n        cell_coord = (0, 0)\n        column = row = 0\n\n        for child in children:\n            child_styles = child.styles\n            column_span = child_styles.column_span or 1\n            row_span = child_styles.row_span or 1\n            # Find a slot where this cell fits\n            # A cell on a previous row may have a row span\n            while True:\n                column, row = cell_coord\n                coords = widget_coords(column, row, column_span, row_span)\n                if cell_map.keys().isdisjoint(coords):\n                    for coord in coords:\n                        cell_map[coord] = (child, coord == cell_coord)\n                    cell_size_map[child] = (\n                        column,\n                        row,\n                        column_span - 1,\n                        row_span - 1,\n                    )\n                    break\n                else:\n                    cell_coord = next_coord()\n                    continue\n            cell_coord = next_coord()\n\n        # Resolve columns / rows\n        columns = resolve(\n            repeat_scalars(column_scalars, table_size_columns),\n            size.width,\n            gutter_vertical,\n            size,\n            viewport,\n        )\n        rows = resolve(\n            repeat_scalars(\n                row_scalars, table_size_rows if table_size_rows else row + 1\n            ),\n            size.height,\n            gutter_horizontal,\n            size,\n            viewport,\n        )\n\n        placements: list[WidgetPlacement] = []\n        add_placement = placements.append\n        fraction_unit = Fraction(1)\n        widgets: list[Widget] = []\n        add_widget = widgets.append\n        max_column = len(columns) - 1\n        max_row = len(rows) - 1\n        margin = Spacing()\n        for widget, (column, row, column_span, row_span) in cell_size_map.items():\n            x = columns[column][0]\n            if row > max_row:\n                break\n            y = rows[row][0]\n            x2, cell_width = columns[min(max_column, column + column_span)]\n            y2, cell_height = rows[min(max_row, row + row_span)]\n            cell_size = Size(cell_width + x2 - x, cell_height + y2 - y)\n            width, height, margin = widget._get_box_model(\n                cell_size,\n                viewport,\n                fraction_unit,\n            )\n            region = (\n                Region(x, y, int(width + margin.width), int(height + margin.height))\n                .shrink(margin)\n                .clip_size(cell_size)\n            )\n            add_placement(WidgetPlacement(region, margin, widget))\n            add_widget(widget)\n\n        return (placements, set(widgets))\n", "path": "src/textual/layouts/grid.py"}]}