Add example to compare all heights.

docs/examples/styles/height_comparison.py

@@ -0,0 +1,28 @@
+from textual.app import App
+from textual.containers import Vertical
+from textual.widgets import Placeholder, Label, Static
+
+
+class VerticalRuler(Static):
+    def compose(self):
+        ruler_text = "\n".join(map(str, range(1, 100)))
+        yield Label(ruler_text)
+
+
+class HeightComparisonApp(App):
+    def compose(self):
+        yield Vertical(
+            Placeholder(id="cells"),    # (1)!
+            Placeholder(id="percent"),
+            Placeholder(id="w"),
+            Placeholder(id="h"),
+            Placeholder(id="vw"),
+            Placeholder(id="vh"),
+            Placeholder(id="auto"),
+            Placeholder(id="fr1"),
+            Placeholder(id="fr2"),
+        )
+        yield VerticalRuler()
+
+
+app = HeightComparisonApp(css_path="height_comparison.css")