diff --git a/src/textual/css/_style_properties.py b/src/textual/css/_style_properties.py
index e91282af3..10c8f9f8a 100644
--- a/src/textual/css/_style_properties.py
+++ b/src/textual/css/_style_properties.py
@@ -220,9 +220,9 @@ class ScalarListProperty:
         percent_unit: The dimension to which percentage scalars will be relative to.
     """
 
-    def __init__(self, children: bool = False, percent_unit: Unit) -> None:
-        self.children = children
+    def __init__(self, percent_unit: Unit, children: bool = False) -> None:
         self.percent_unit = percent_unit
+        self.children = children
 
     def __set_name__(self, owner: Styles, name: str) -> None:
         self.name = name
diff --git a/src/textual/css/styles.py b/src/textual/css/styles.py
index 29cacf7cb..4a3691bcc 100644
--- a/src/textual/css/styles.py
+++ b/src/textual/css/styles.py
@@ -287,8 +287,8 @@ class StylesBase(ABC):
     content_align_vertical = StringEnumProperty(VALID_ALIGN_VERTICAL, "top")
     content_align = AlignProperty()
 
-    grid_rows = ScalarListProperty(children=True, percent_unit=Unit.HEIGHT)
-    grid_columns = ScalarListProperty(children=True, percent_unit=Unit.WIDTH)
+    grid_rows = ScalarListProperty(percent_unit=Unit.HEIGHT, children=True)
+    grid_columns = ScalarListProperty(percent_unit=Unit.WIDTH, children=True)
 
     grid_size_columns = IntegerProperty(default=1, layout=True, children=True)
     grid_size_rows = IntegerProperty(default=0, layout=True, children=True)