Add default background to panel, reduce nesting

osu.Game/Screens/OnlinePlay/Lounge/Components/DrawableRoom.cs

@@ -126,15 +126,23 @@ namespace osu.Game.Screens.OnlinePlay.Lounge.Components
         {
             Children = new Drawable[]
             {
-                new Container
+                // This resolves internal 1px gaps due to applying the (parenting) corner radius and masking across multiple filling background sprites.
+                new BufferedContainer
                 {
                     RelativeSizeAxes = Axes.Both,
                     Children = new Drawable[]
                     {
+                        new Box
+                        {
+                            RelativeSizeAxes = Axes.Both,
+                            Colour = Color4Extensions.FromHex(@"#27302E"),
+                        },
                         new OnlinePlayBackgroundSprite(BeatmapSetCoverType.List)
                         {
                             RelativeSizeAxes = Axes.Both
                         },
+                    }
+                },
                 new Container
                 {
                     Name = @"Room content",
@@ -284,8 +292,6 @@ namespace osu.Game.Screens.OnlinePlay.Lounge.Components
                         },
                     },
                 },
-                    }
-                },
                 new StatusColouredContainer(transition_duration)
                 {
                     RelativeSizeAxes = Axes.Both,