Tidy up how SettingsSubsection headings are created

Previously we were always making header content in the base class then
overwriting it, which felt ick.

osu.Game/Overlays/Settings/Sections/InputSubsection.cs

@@ -30,6 +30,8 @@ namespace osu.Game.Overlays.Settings.Sections
 
         private readonly BindableBool handlerEnabled = new BindableBool();
 
+        private ToggleableHeader header = null!;
+
         public InputSubsection(InputHandler handler)
         {
             this.handler = handler;
@@ -37,14 +39,10 @@ namespace osu.Game.Overlays.Settings.Sections
             FlowContent.AlwaysPresent = true;
         }
 
-        [BackgroundDependencyLoader]
-        private void load()
+        protected override Drawable CreateHeader() => header = new ToggleableHeader(Header, IsToggleable)
         {
-            HeaderContainer.Child = new ToggleableHeader(Header, IsToggleable)
-            {
-                Current = { BindTarget = handlerEnabled },
-            };
-        }
+            Current = { BindTarget = handlerEnabled },
+        };
 
         protected override void LoadComplete()
         {
@@ -58,7 +56,7 @@ namespace osu.Game.Overlays.Settings.Sections
         {
             // set negative bottom margin to not have too much vertical gap between disabled input subsections.
             bool negativeBottomMargin = !handlerEnabled.Value || FlowContent.Count == 0;
-            HeaderContainer.TransformTo(nameof(Margin), new MarginPadding { Bottom = negativeBottomMargin ? -15 : 0 }, 300, Easing.OutQuint);
+            header.TransformTo(nameof(Margin), new MarginPadding { Bottom = negativeBottomMargin ? -VERTICAL_PADDING : 0 }, 300, Easing.OutQuint);
 
             FlowContent.ClearTransforms();
 
@@ -92,6 +90,11 @@ namespace osu.Game.Overlays.Settings.Sections
 
             public ToggleableHeader(LocalisableString text, bool toggleable)
             {
+                Padding = SettingsPanel.CONTENT_PADDING;
+
+                RelativeSizeAxes = Axes.X;
+                AutoSizeAxes = Axes.Y;
+
                 this.text = text;
                 this.toggleable = toggleable;
             }
@@ -105,8 +108,6 @@ namespace osu.Game.Overlays.Settings.Sections
             [BackgroundDependencyLoader]
             private void load()
             {
-                AutoSizeAxes = Axes.Both;
-
                 InternalChildren = new Drawable[]
                 {
                     switchButton = new SwitchButton

osu.Game/Overlays/Settings/SettingsSubsection.cs

@@ -14,12 +14,12 @@ namespace osu.Game.Overlays.Settings
 {
     public abstract partial class SettingsSubsection : FillFlowContainer, IFilterable
     {
+        public const float VERTICAL_PADDING = (header_height - header_font_size) * 0.5f;
+
         protected override Container<Drawable> Content => FlowContent;
 
         protected readonly FillFlowContainer FlowContent;
 
-        protected Container HeaderContainer { get; private set; } = null!;
-
         protected abstract LocalisableString Header { get; }
 
         public virtual IEnumerable<LocalisableString> FilterTerms => new[] { Header };
@@ -53,25 +53,22 @@ namespace osu.Game.Overlays.Settings
         [BackgroundDependencyLoader]
         private void load()
         {
-            AddRangeInternal(new Drawable[]
+            AddRangeInternal(new[]
             {
-                HeaderContainer = new Container
-                {
-                    RelativeSizeAxes = Axes.X,
-                    AutoSizeAxes = Axes.Y,
-                    Padding = SettingsPanel.CONTENT_PADDING,
-                    Children = new[]
-                    {
-                        new OsuSpriteText
-                        {
-                            Text = Header,
-                            Font = OsuFont.GetFont(size: header_font_size),
-                            Margin = new MarginPadding { Vertical = (header_height - header_font_size) * 0.5f },
-                        },
-                    },
-                },
+                CreateHeader(),
                 FlowContent
             });
         }
+
+        protected virtual Drawable CreateHeader()
+        {
+            return new OsuSpriteText
+            {
+                Text = Header,
+                Font = OsuFont.GetFont(size: header_font_size),
+                Margin = new MarginPadding { Vertical = VERTICAL_PADDING },
+                Padding = SettingsPanel.CONTENT_PADDING,
+            };
+        }
     }
 }