fix for percentage scalars

sandbox/will/fill.py

@@ -0,0 +1,10 @@
+from textual.app import App, ComposeResult
+from textual.widgets import Static
+
+
+class FillApp(App):
+    def compose(self) -> ComposeResult:
+        yield Static("Hello")
+
+
+app = FillApp(css_path="fill.css")