Align osu!catch playfield with stable 1:1

osu.Game.Rulesets.Catch/UI/CatchPlayfieldAdjustmentContainer.cs

@@ -17,8 +17,12 @@ public class CatchPlayfieldAdjustmentContainer : PlayfieldAdjustmentContainer
 
         public CatchPlayfieldAdjustmentContainer()
         {
-            Anchor = Anchor.TopCentre;
-            Origin = Anchor.TopCentre;
+            // because we are using centre anchor/origin, we will need to limit visibility in the future
+            // to ensure tall windows do not get a readability advantage.
+            // it may be possible to bake the catch-specific offsets (-100..340 mentioned below) into new values
+            // which are compatible with TopCentre alignment.
+            Anchor = Anchor.Centre;
+            Origin = Anchor.Centre;
 
             Size = new Vector2(playfield_size_adjust);
 
@@ -29,7 +33,7 @@ public CatchPlayfieldAdjustmentContainer()
                 RelativeSizeAxes = Axes.Both,
                 FillMode = FillMode.Fit,
                 FillAspectRatio = 4f / 3,
-                Child = content = new ScalingContainer { RelativeSizeAxes = Axes.Both }
+                Child = content = new ScalingContainer { RelativeSizeAxes = Axes.Both, }
             };
         }
 
@@ -42,8 +46,14 @@ protected override void Update()
             {
                 base.Update();
 
+                // in stable, fruit fall vertically from -100 to 340.
+                // to emulate this, we want to make our playfield 440 gameplay pixels high.
+                // we then offset it -100 vertically in the position set below.
+                const float stable_v_offset_ratio = 440 / 384f;
+
                 Scale = new Vector2(Parent.ChildSize.X / CatchPlayfield.WIDTH);
-                Size = Vector2.Divide(Vector2.One, Scale);
+                Position = new Vector2(0, -100 * stable_v_offset_ratio + Scale.X);
+                Size = Vector2.Divide(new Vector2(1, stable_v_offset_ratio), Scale);
             }
         }
     }