fix: allow integer for fractional styles

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - `Pilot.click`/`Pilot.hover` can't use `Screen` as a selector https://github.com/Textualize/textual/issues/3395
 - App exception when a `Tree` is initialized/mounted with `disabled=True` https://github.com/Textualize/textual/issues/3407
+- Fixed fractional styles to allow integer values https://github.com/Textualize/textual/issues/3414
 
 ### Added
 

src/textual/css/_style_properties.py

@@ -1063,8 +1063,8 @@ def __set__(self, obj: StylesBase, value: float | str | None) -> None:
                 obj.refresh(children=self.children)
             return
 
-        if isinstance(value, float):
-            float_value = value
+        if isinstance(value, (int, float)):
+            float_value = float(value)
         elif isinstance(value, str) and value.endswith("%"):
             float_value = float(Scalar.parse(value).value) / 100
         else:

tests/css/test_styles.py

@@ -148,6 +148,13 @@ def test_opacity_set_invalid_type_error():
         styles.text_opacity = "invalid value"
 
 
+def test_opacity_set_allows_integer_value():
+    """Regression test for https://github.com/Textualize/textual/issues/3414"""
+    styles = RenderStyles(DOMNode(), Styles(), Styles())
+    styles.text_opacity = 0
+    assert styles.text_opacity == 0.0
+
+
 @pytest.mark.parametrize(
     "size_dimension_input,size_dimension_expected_output",
     [