diff --git a/BuildTime.txt b/BuildTime.txt
index f4c10f2..da9c901 100644
--- a/BuildTime.txt
+++ b/BuildTime.txt
@@ -1 +1 @@
-2026-03-26 20:06:05
\ No newline at end of file
+2026-03-26 20:36:31
\ No newline at end of file
diff --git a/GitCommit.txt b/GitCommit.txt
index 6e0ab9a..9cf38b9 100644
--- a/GitCommit.txt
+++ b/GitCommit.txt
@@ -1 +1 @@
-2c2f93c
\ No newline at end of file
+2c2ee0f
\ No newline at end of file
diff --git a/Gui/Apps/Settings.cs b/Gui/Apps/Settings.cs
index b5c7250..dbe08c6 100644
--- a/Gui/Apps/Settings.cs
+++ b/Gui/Apps/Settings.cs
@@ -164,6 +164,14 @@ namespace CMLeonOS.Gui.Apps
             SettingsManager.GUI_MouseSensitivity = value;
         }
 
+        private void ThemeChanged(int index, string themeName)
+        {
+            SettingsManager.GUI_Theme = themeName;
+            UITheme.ApplyTheme(themeName);
+            UITheme.RefreshOpenWindows(wm);
+            ShowAppearanceCategory();
+        }
+
         private void ShowAppearanceCategory()
         {
             if (currentCategoryWindow != null)
@@ -193,16 +201,36 @@ namespace CMLeonOS.Gui.Apps
             skipToGui.CheckBoxChanged = SkipToGuiChanged;
             wm.AddWindow(skipToGui);
 
-            appearance.DrawString("Wallpaper", Color.Gray, 12, 132);
-            appearance.DrawString(GetWallpaperLabel(), Color.Black, 12, 152);
-            appearance.DrawString("Use a BMP file or restore the default wallpaper.", Color.Gray, 12, 170);
+            appearance.DrawString("Theme", Color.Gray, 12, 126);
 
-            Button chooseWallpaper = new Button(appearance, 12, 192, 132, 24);
+            Dropdown themeDropdown = new Dropdown(appearance, 12, 146, 180, 24);
+            string[] themes = UITheme.GetThemeNames();
+            for (int i = 0; i < themes.Length; i++)
+            {
+                themeDropdown.Items.Add(themes[i]);
+            }
+            themeDropdown.RefreshItems();
+            for (int i = 0; i < themes.Length; i++)
+            {
+                if (themes[i] == SettingsManager.GUI_Theme)
+                {
+                    themeDropdown.SelectedIndex = i;
+                    break;
+                }
+            }
+            themeDropdown.SelectionChanged = ThemeChanged;
+            wm.AddWindow(themeDropdown);
+
+            appearance.DrawString("Wallpaper", Color.Gray, 12, 184);
+            appearance.DrawString(GetWallpaperLabel(), Color.Black, 12, 204);
+            appearance.DrawString("Use a BMP file or restore the default wallpaper.", Color.Gray, 12, 222);
+
+            Button chooseWallpaper = new Button(appearance, 12, 244, 132, 24);
             chooseWallpaper.Text = "Choose BMP";
             chooseWallpaper.OnClick = (_, _) => OpenWallpaperBrowser();
             wm.AddWindow(chooseWallpaper);
 
-            Button defaultWallpaper = new Button(appearance, 154, 192, 132, 24);
+            Button defaultWallpaper = new Button(appearance, 154, 244, 132, 24);
             defaultWallpaper.Text = "Use Default";
             defaultWallpaper.OnClick = (_, _) => ApplyWallpaper(string.Empty);
             wm.AddWindow(defaultWallpaper);
diff --git a/Gui/Gui.cs b/Gui/Gui.cs
index b296953..9429ec1 100644
--- a/Gui/Gui.cs
+++ b/Gui/Gui.cs
@@ -16,6 +16,7 @@
 
 using CMLeonOS;
 using CMLeonOS.Logger;
+using CMLeonOS.Settings;
 using System;
 
 namespace CMLeonOS.Gui
@@ -51,6 +52,9 @@ namespace CMLeonOS.Gui
             Console.WriteLine("Loading apps...");
             AppManager.LoadAllApps();
 
+            SettingsManager.LoadSettings();
+            UILib.UITheme.ApplyTheme(SettingsManager.GUI_Theme);
+
             ProcessManager.AddProcess(windowManager);
 
             ProcessManager.AddProcess(windowManager, new SettingsService()).Start();
diff --git a/Gui/UILib/AppWindow.cs b/Gui/UILib/AppWindow.cs
index ce2dd81..b04b235 100644
--- a/Gui/UILib/AppWindow.cs
+++ b/Gui/UILib/AppWindow.cs
@@ -357,5 +357,11 @@ namespace CMLeonOS.Gui.UILib
             }
             wm.Update(decorationWindow);
         }
+
+        internal void RefreshTheme()
+        {
+            wm.Update(this);
+            RenderDecoration();
+        }
     }
 }
diff --git a/Gui/UILib/TreeNode.cs b/Gui/UILib/TreeNode.cs
index 375c150..d7cfde6 100644
--- a/Gui/UILib/TreeNode.cs
+++ b/Gui/UILib/TreeNode.cs
@@ -13,6 +13,9 @@ namespace CMLeonOS.Gui.UILib
         internal string Text { get; set; }
         internal object Tag { get; set; }
         internal bool Expanded { get; set; } = false;
+        internal int AnimatedChildCount { get; set; } = 0;
+        internal bool ExpandingAnimation { get; set; } = false;
+        internal bool CollapsingAnimation { get; set; } = false;
         internal List<TreeNode> Children { get; } = new List<TreeNode>();
     }
 }
diff --git a/Gui/UILib/TreeView.cs b/Gui/UILib/TreeView.cs
index 88c675c..5957b44 100644
--- a/Gui/UILib/TreeView.cs
+++ b/Gui/UILib/TreeView.cs
@@ -66,9 +66,16 @@ namespace CMLeonOS.Gui.UILib
             visibleNodes.Add(node);
             visibleLevels.Add(level);
 
-            if (node.Expanded)
+            if (node.Expanded || node.ExpandingAnimation || node.CollapsingAnimation)
             {
-                for (int i = 0; i < node.Children.Count; i++)
+                int visibleChildCount = node.Children.Count;
+
+                if (node.ExpandingAnimation || node.CollapsingAnimation)
+                {
+                    visibleChildCount = Math.Min(node.Children.Count, Math.Max(0, node.AnimatedChildCount));
+                }
+
+                for (int i = 0; i < visibleChildCount; i++)
                 {
                     AddVisibleNode(node.Children[i], level + 1);
                 }
@@ -90,7 +97,19 @@ namespace CMLeonOS.Gui.UILib
 
             if (node.Children.Count > 0 && x >= indentX && x <= indentX + 10)
             {
-                node.Expanded = !node.Expanded;
+                if (node.Expanded || node.ExpandingAnimation)
+                {
+                    node.ExpandingAnimation = false;
+                    node.CollapsingAnimation = true;
+                    node.AnimatedChildCount = node.Children.Count;
+                }
+                else
+                {
+                    node.Expanded = true;
+                    node.CollapsingAnimation = false;
+                    node.ExpandingAnimation = true;
+                    node.AnimatedChildCount = 0;
+                }
                 Render();
                 return;
             }
@@ -106,6 +125,7 @@ namespace CMLeonOS.Gui.UILib
             DrawRectangle(0, 0, Width, Height, Border);
 
             BuildVisibleNodes();
+            bool hasAnimation = false;
 
             int maxRows = Math.Min(visibleNodes.Count, Math.Max(0, Height / RowHeight));
             for (int i = 0; i < maxRows; i++)
@@ -124,7 +144,7 @@ namespace CMLeonOS.Gui.UILib
                 {
                     DrawRectangle(indentX, rowY + 6, 10, 10, Border);
                     DrawHorizontalLine(6, indentX + 2, rowY + 11, Foreground);
-                    if (!node.Expanded)
+                    if (!node.Expanded || node.CollapsingAnimation)
                     {
                         DrawVerticalLine(6, indentX + 5, rowY + 8, Foreground);
                     }
@@ -134,7 +154,46 @@ namespace CMLeonOS.Gui.UILib
                 DrawString(node.Text, Foreground, textX, rowY + 3);
             }
 
+            UpdateNodeAnimations(Nodes, ref hasAnimation);
+
+            if (hasAnimation)
+            {
+                WM.UpdateQueue.Enqueue(this);
+            }
+
             WM.Update(this);
         }
+
+        private void UpdateNodeAnimations(List<TreeNode> nodes, ref bool hasAnimation)
+        {
+            for (int i = 0; i < nodes.Count; i++)
+            {
+                TreeNode node = nodes[i];
+
+                if (node.ExpandingAnimation)
+                {
+                    hasAnimation = true;
+                    node.AnimatedChildCount++;
+                    if (node.AnimatedChildCount >= node.Children.Count)
+                    {
+                        node.AnimatedChildCount = node.Children.Count;
+                        node.ExpandingAnimation = false;
+                    }
+                }
+                else if (node.CollapsingAnimation)
+                {
+                    hasAnimation = true;
+                    node.AnimatedChildCount--;
+                    if (node.AnimatedChildCount <= 0)
+                    {
+                        node.AnimatedChildCount = 0;
+                        node.CollapsingAnimation = false;
+                        node.Expanded = false;
+                    }
+                }
+
+                UpdateNodeAnimations(node.Children, ref hasAnimation);
+            }
+        }
     }
 }
diff --git a/Gui/UILib/UITheme.cs b/Gui/UILib/UITheme.cs
index a5069ca..f84de0d 100644
--- a/Gui/UILib/UITheme.cs
+++ b/Gui/UILib/UITheme.cs
@@ -20,23 +20,136 @@ namespace CMLeonOS.Gui.UILib
 {
     internal static class UITheme
     {
-        internal static readonly Color WindowTitleBackground = Color.FromArgb(26, 34, 46);
-        internal static readonly Color WindowTitleTopHighlight = Color.FromArgb(52, 67, 90);
-        internal static readonly Color WindowTitleBottomBorder = Color.FromArgb(14, 18, 26);
-        internal static readonly Color WindowTitleText = Color.FromArgb(239, 244, 252);
-        internal static readonly Color WindowButtonBackground = Color.FromArgb(38, 49, 66);
+        internal static Color WindowTitleBackground { get; private set; }
+        internal static Color WindowTitleTopHighlight { get; private set; }
+        internal static Color WindowTitleBottomBorder { get; private set; }
+        internal static Color WindowTitleText { get; private set; }
+        internal static Color WindowButtonBackground { get; private set; }
 
-        internal static readonly Color Surface = Color.FromArgb(245, 248, 252);
-        internal static readonly Color SurfaceMuted = Color.FromArgb(228, 235, 245);
-        internal static readonly Color SurfaceBorder = Color.FromArgb(149, 164, 183);
-        internal static readonly Color TextPrimary = Color.FromArgb(33, 43, 56);
-        internal static readonly Color TextSecondary = Color.FromArgb(96, 109, 128);
+        internal static Color Surface { get; private set; }
+        internal static Color SurfaceMuted { get; private set; }
+        internal static Color SurfaceBorder { get; private set; }
+        internal static Color TextPrimary { get; private set; }
+        internal static Color TextSecondary { get; private set; }
 
-        internal static readonly Color Accent = Color.FromArgb(45, 117, 222);
-        internal static readonly Color AccentDark = Color.FromArgb(28, 89, 184);
-        internal static readonly Color AccentLight = Color.FromArgb(204, 225, 255);
+        internal static Color Accent { get; private set; }
+        internal static Color AccentDark { get; private set; }
+        internal static Color AccentLight { get; private set; }
 
-        internal static readonly Color Success = Color.FromArgb(45, 152, 99);
-        internal static readonly Color Warning = Color.FromArgb(210, 139, 54);
+        internal static Color Success { get; private set; }
+        internal static Color Warning { get; private set; }
+
+        internal static string CurrentThemeName { get; private set; } = "Default";
+
+        internal static string[] GetThemeNames()
+        {
+            return new string[] { "Default", "Graphite", "Forest" };
+        }
+
+        internal static void ApplyTheme(string themeName)
+        {
+            string name = string.IsNullOrWhiteSpace(themeName) ? "Default" : themeName.Trim();
+
+            switch (name)
+            {
+                case "Graphite":
+                    WindowTitleBackground = Color.FromArgb(31, 34, 40);
+                    WindowTitleTopHighlight = Color.FromArgb(62, 69, 81);
+                    WindowTitleBottomBorder = Color.FromArgb(18, 20, 24);
+                    WindowTitleText = Color.FromArgb(239, 242, 247);
+                    WindowButtonBackground = Color.FromArgb(47, 53, 61);
+
+                    Surface = Color.FromArgb(236, 239, 244);
+                    SurfaceMuted = Color.FromArgb(214, 220, 228);
+                    SurfaceBorder = Color.FromArgb(124, 134, 149);
+                    TextPrimary = Color.FromArgb(36, 42, 52);
+                    TextSecondary = Color.FromArgb(92, 101, 115);
+
+                    Accent = Color.FromArgb(90, 131, 212);
+                    AccentDark = Color.FromArgb(64, 100, 176);
+                    AccentLight = Color.FromArgb(205, 220, 247);
+
+                    Success = Color.FromArgb(61, 145, 108);
+                    Warning = Color.FromArgb(196, 138, 60);
+                    CurrentThemeName = "Graphite";
+                    break;
+
+                case "Forest":
+                    WindowTitleBackground = Color.FromArgb(24, 48, 36);
+                    WindowTitleTopHighlight = Color.FromArgb(60, 98, 77);
+                    WindowTitleBottomBorder = Color.FromArgb(13, 28, 20);
+                    WindowTitleText = Color.FromArgb(240, 248, 243);
+                    WindowButtonBackground = Color.FromArgb(38, 67, 52);
+
+                    Surface = Color.FromArgb(242, 248, 244);
+                    SurfaceMuted = Color.FromArgb(220, 232, 224);
+                    SurfaceBorder = Color.FromArgb(134, 160, 145);
+                    TextPrimary = Color.FromArgb(33, 53, 41);
+                    TextSecondary = Color.FromArgb(95, 116, 104);
+
+                    Accent = Color.FromArgb(53, 144, 98);
+                    AccentDark = Color.FromArgb(37, 112, 74);
+                    AccentLight = Color.FromArgb(202, 236, 217);
+
+                    Success = Color.FromArgb(42, 153, 92);
+                    Warning = Color.FromArgb(191, 137, 55);
+                    CurrentThemeName = "Forest";
+                    break;
+
+                default:
+                    WindowTitleBackground = Color.FromArgb(26, 34, 46);
+                    WindowTitleTopHighlight = Color.FromArgb(52, 67, 90);
+                    WindowTitleBottomBorder = Color.FromArgb(14, 18, 26);
+                    WindowTitleText = Color.FromArgb(239, 244, 252);
+                    WindowButtonBackground = Color.FromArgb(38, 49, 66);
+
+                    Surface = Color.FromArgb(245, 248, 252);
+                    SurfaceMuted = Color.FromArgb(228, 235, 245);
+                    SurfaceBorder = Color.FromArgb(149, 164, 183);
+                    TextPrimary = Color.FromArgb(33, 43, 56);
+                    TextSecondary = Color.FromArgb(96, 109, 128);
+
+                    Accent = Color.FromArgb(45, 117, 222);
+                    AccentDark = Color.FromArgb(28, 89, 184);
+                    AccentLight = Color.FromArgb(204, 225, 255);
+
+                    Success = Color.FromArgb(45, 152, 99);
+                    Warning = Color.FromArgb(210, 139, 54);
+                    CurrentThemeName = "Default";
+                    break;
+            }
+        }
+
+        internal static void RefreshOpenWindows(CMLeonOS.Gui.WindowManager wm)
+        {
+            if (wm == null)
+            {
+                return;
+            }
+
+            for (int i = 0; i < wm.Windows.Count; i++)
+            {
+                CMLeonOS.Gui.Window window = wm.Windows[i];
+                if (window is AppWindow appWindow)
+                {
+                    appWindow.RefreshTheme();
+                }
+                else if (window is Control control)
+                {
+                    control.Render();
+                }
+                else
+                {
+                    wm.Update(window);
+                }
+            }
+
+            wm.RerenderAll();
+        }
+
+        static UITheme()
+        {
+            ApplyTheme("Default");
+        }
     }
 }
diff --git a/Settings/Settings.cs b/Settings/Settings.cs
index dc6c34c..f1041c1 100644
--- a/Settings/Settings.cs
+++ b/Settings/Settings.cs
@@ -39,6 +39,7 @@ namespace CMLeonOS.Settings
             { "GUI_ScreenWidth", "1280" },
             { "GUI_ScreenHeight", "800" },
             { "GUI_WallpaperPath", "" },
+            { "GUI_Theme", "Default" },
             { "GUI_DarkNotepad", "false" },
             { "SkipToGui", "false" }
         };
@@ -208,6 +209,23 @@ namespace CMLeonOS.Settings
             }
         }
 
+        public static string GUI_Theme
+        {
+            get
+            {
+                if (settings.TryGetValue("GUI_Theme", out string value))
+                {
+                    return string.IsNullOrWhiteSpace(value) ? "Default" : value;
+                }
+                return "Default";
+            }
+            set
+            {
+                settings["GUI_Theme"] = string.IsNullOrWhiteSpace(value) ? "Default" : value;
+                SaveSettings();
+            }
+        }
+
         public static bool GUI_DarkNotepad
         {
             get