fix for auto width and relative dimensions

tests/snapshot_tests/snapshot_apps/columns_height.py

@@ -0,0 +1,37 @@
+from textual.app import App, ComposeResult
+from textual.containers import Horizontal
+from textual.widgets import Static
+
+
+class HeightApp(App[None]):
+
+    CSS = """
+    Horizontal {
+        border: solid red;
+        height: auto;
+    }
+
+    Static {
+        border: solid green;
+        width: auto;
+    }
+
+    #fill_parent {
+        height: 100%;
+    }
+
+    #static {
+        height: 16;
+    }
+    """
+
+    def compose(self) -> ComposeResult:
+        yield Horizontal(
+            Static("As tall as container", id="fill_parent"),
+            Static("This has default\nheight\nbut a\nfew lines"),
+            Static("I have a static height", id="static"),
+        )
+
+
+if __name__ == "__main__":
+    HeightApp().run()

tests/snapshot_tests/snapshot_apps/order_independence.py

@@ -16,7 +16,7 @@ class Body1(Vertical):
 
 class Body2(Vertical):
     def compose(self) -> ComposeResult:
-        yield Label("I'm sorry, Dave. I'm afraid I can't do that. " * 300)
+        yield Label("My God! It's full of stars! " * 300)
 
 
 class Good(Screen):
@@ -52,6 +52,10 @@ class Layers(App[None]):
         background: red;
         color: yellow;
     }
+
+    Body2 {
+        background: green;
+    }
     """
 
     SCREENS = {"good": Good, "bad": Bad}

tests/snapshot_tests/test_snapshots.py

@@ -139,15 +139,18 @@ def test_multiple_css(snap_compare):
 
 
 def test_order_independence(snap_compare):
-    # Interaction between multiple CSS files and app-level/classvar CSS
     assert snap_compare("snapshot_apps/order_independence.py")
 
 
 def test_order_independence_toggle(snap_compare):
-    # Interaction between multiple CSS files and app-level/classvar CSS
     assert snap_compare("snapshot_apps/order_independence.py", press="t,_")
 
 
+def test_columns_height(snap_compare):
+    # Interaction with height auto, and relative heights to make columns
+    assert snap_compare("snapshot_apps/columns_height.py")
+
+
 # --- Other ---