fix for percentage dimensions

CHANGELOG.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - `SelectionList` option IDs are usable as soon as the widget is instantiated https://github.com/Textualize/textual/issues/3903
 - Fix issue with `Strip.crop` when crop window start aligned with strip end https://github.com/Textualize/textual/pull/3998
 - Fixed Strip.crop_extend https://github.com/Textualize/textual/pull/4011
+- Fix for percentage dimensions https://github.com/Textualize/textual/pull/4037
 
 
 ## [0.47.1] - 2023-01-05

src/textual/css/scalar.py

@@ -37,8 +37,6 @@ class Unit(Enum):
     AUTO = 8
 
 
-UNIT_EXCLUDES_BORDER = {Unit.CELLS, Unit.FRACTION, Unit.VIEW_WIDTH, Unit.VIEW_HEIGHT}
-
 UNIT_SYMBOL = {
     Unit.CELLS: "",
     Unit.FRACTION: "fr",
@@ -206,10 +204,6 @@ def is_fraction(self) -> bool:
         """Check if the unit is a fraction."""
         return self.unit == Unit.FRACTION
 
-    @property
-    def excludes_border(self) -> bool:
-        return self.unit in UNIT_EXCLUDES_BORDER
-
     @property
     def cells(self) -> int | None:
         """Check if the unit is explicit cells."""

src/textual/widget.py

@@ -1075,8 +1075,6 @@ def _get_box_model(
 
         # Container minus padding and border
         content_container = container - gutter.totals
-        # The container including the content
-        sizing_container = content_container if is_border_box else container
 
         if styles.width is None:
             # No width specified, fill available space
@@ -1099,25 +1097,21 @@ def _get_box_model(
             # An explicit width
             styles_width = styles.width
             content_width = styles_width.resolve(
-                sizing_container - styles.margin.totals, viewport, width_fraction
+                container - styles.margin.totals, viewport, width_fraction
             )
-            if is_border_box and styles_width.excludes_border:
+            if is_border_box:
                 content_width -= gutter.width
 
         if styles.min_width is not None:
             # Restrict to minimum width, if set
-            min_width = styles.min_width.resolve(
-                content_container, viewport, width_fraction
-            )
+            min_width = styles.min_width.resolve(container, viewport, width_fraction)
             if is_border_box:
                 min_width -= gutter.width
             content_width = max(content_width, min_width, Fraction(0))
 
         if styles.max_width is not None:
             # Restrict to maximum width, if set
-            max_width = styles.max_width.resolve(
-                content_container, viewport, width_fraction
-            )
+            max_width = styles.max_width.resolve(container, viewport, width_fraction)
             if is_border_box:
                 max_width -= gutter.width
             content_width = min(content_width, max_width)
@@ -1143,25 +1137,21 @@ def _get_box_model(
             styles_height = styles.height
             # Explicit height set
             content_height = styles_height.resolve(
-                sizing_container - styles.margin.totals, viewport, height_fraction
+                container - styles.margin.totals, viewport, height_fraction
             )
-            if is_border_box and styles_height.excludes_border:
+            if is_border_box:
                 content_height -= gutter.height
 
         if styles.min_height is not None:
             # Restrict to minimum height, if set
-            min_height = styles.min_height.resolve(
-                content_container, viewport, height_fraction
-            )
+            min_height = styles.min_height.resolve(container, viewport, height_fraction)
             if is_border_box:
                 min_height -= gutter.height
             content_height = max(content_height, min_height, Fraction(0))
 
         if styles.max_height is not None:
             # Restrict maximum height, if set
-            max_height = styles.max_height.resolve(
-                content_container, viewport, height_fraction
-            )
+            max_height = styles.max_height.resolve(container, viewport, height_fraction)
             if is_border_box:
                 max_height -= gutter.height
             content_height = min(content_height, max_height)