Add NeutralBaseColor to GlobalState and FDT

src/Core/Components/DesignSystemProvider/FluentDesignTheme.razor

@@ -1,4 +1,4 @@
-@namespace Microsoft.FluentUI.AspNetCore.Components
+@namespace Microsoft.FluentUI.AspNetCore.Components
 
-<fluent-design-theme id="@Id" mode="@GetMode()" primary-color="@GetColor()" storage-name="@StorageName" />
-@ChildContent
+<fluent-design-theme id="@Id" mode="@GetMode()" primary-color="@GetColor()" neutral-base-color="@NeutralBaseColor" storage-name="@StorageName" />
+@ChildContent

src/Core/Components/DesignSystemProvider/FluentDesignTheme.razor.cs

@@ -77,6 +77,12 @@ public partial class FluentDesignTheme : ComponentBase
     [Parameter]
     public EventCallback<OfficeColor?> OfficeColorChanged { get; set; }
 
+    [Parameter]
+    public string? NeutralBaseColor { get; set; }
+
+    [Parameter]
+    public EventCallback<string?> NeutralBaseColorChanged { get; set; }
+
     /// <summary>
     /// Gets or sets the local storage name to save and retrieve the <see cref="Mode"/> and the <see cref="OfficeColor"/> / <see cref="CustomColor"/>.
     /// </summary> 
@@ -175,6 +181,12 @@ public async Task OnChangeRaisedAsync(string name, string value)
                     }
                 }
 
+                break;
+            case "neutral-base-color":
+                if (value.StartsWith('#'))
+                {
+                    GlobalDesign.SetNeutralColor(value);
+                }
                 break;
         }
     }
@@ -256,13 +268,24 @@ private async Task ApplyLocalStorageValuesAsync(DataLocalStorage? theme)
                 await OnChangeRaisedAsync("primary-color", theme.PrimaryColor);
             }
         }
+
+        // Neutral base color
+        if (!string.IsNullOrEmpty(theme?.NeutralBaseColor))
+        {
+            if (theme.NeutralBaseColor.StartsWith('#'))
+            {
+                GlobalDesign.SetNeutralColor(theme.NeutralBaseColor);
+            }
+            await OnChangeRaisedAsync("neutral-base-color", theme.NeutralBaseColor);
+        }
     }
 
     /// <summary />
     private class DataLocalStorage
     {
         public string? Mode { get; set; }
         public string? PrimaryColor { get; set; }
+        public string? NeutralBaseColor { get; set; }
     }
 
     /// <summary />

src/Core/GlobalState.cs

@@ -1,3 +1,7 @@
+// ------------------------------------------------------------------------
+// MIT License - Copyright (c) Microsoft Corporation. All rights reserved.
+// ------------------------------------------------------------------------
+
 using Microsoft.AspNetCore.Components;
 
 namespace Microsoft.FluentUI.AspNetCore.Components;
@@ -16,6 +20,8 @@ public class GlobalState
 
     public string? Color { get; set; }
 
+    public string? NeutralColor { get; set; }
+
     public event Action? OnChange;
 
     public void SetDirection(LocalizationDirection dir)
@@ -42,6 +48,12 @@ public void SetColor(string? color)
         NotifyStateHasChanged();
     }
 
+    public void SetNeutralColor(string? neutralColor)
+    {
+        NeutralColor = neutralColor;
+        NotifyStateHasChanged();
+    }
+
     private void NotifyStateHasChanged()
     {
         OnChange?.Invoke();