hide label when mod is empty

osu.Game/Overlays/Mods/ModSection.cs

@@ -50,6 +50,34 @@ namespace osu.Game.Overlays.Mods
 
                 ButtonsContainer.Children = modContainers;
                 buttons = modContainers.OfType<ModButton>().ToArray();
+
+                Expanded = value.Any();
+            }
+        }
+
+        private bool expanded = true;
+
+        public bool Expanded
+        {
+            set
+            {
+                if (expanded == value) return;
+
+                expanded = value;
+
+                this.ClearTransforms();
+
+                if (expanded)
+                {
+                    this.AutoSizeAxes = Axes.Y;
+                    this.headerLabel.FadeIn(200);
+                }
+                else
+                {
+                    this.AutoSizeAxes = Axes.None;
+                    this.headerLabel.FadeOut(200);
+                    this.ResizeHeightTo(0, 200, Easing.OutQuint);
+                }
             }
         }