diff --git a/src/textual/css/styles.py b/src/textual/css/styles.py
index 211432aadb..8ba4685a0f 100644
--- a/src/textual/css/styles.py
+++ b/src/textual/css/styles.py
@@ -975,7 +975,10 @@ def _update_rules(
         changes = updates + removed
         if not changes:
             return False
-        geometry = any(
+        # Detached styles normalize rules (including mount's prepared copy)
+        # but have no node geometry to invalidate. Keep validation and rule
+        # publication intact; acquire placement effects only for their owner.
+        geometry = self.node is not None and any(
             descriptor.affects_geometry(previous, value)
             for descriptor, key, previous, value in changes
         )
diff --git a/tests/css/test_stylesheet.py b/tests/css/test_stylesheet.py
index f437f935ba..4925e221e9 100644
--- a/tests/css/test_stylesheet.py
+++ b/tests/css/test_stylesheet.py
@@ -100,7 +100,8 @@ async def test_style_batch_keeps_child_damage_separate_and_flushes_interrupted_e
                 parent.styles.refresh(layout=True)
                 with parent.styles.batch_update():
                     parent.styles.color = "green"
-            refresh.assert_called_once_with(layout=False, repaint=True)
+            refresh.assert_called_once_with(repaint=True)
+            assert not child._layout_required
         assert child.rich_style.color == Color.parse("green").rich_color
         with pytest.raises(StyleValueError), parent.styles.batch_update():
             parent.styles.color = "red"