diff --git a/ntfysh_client/NotificationDialog.cs b/ntfysh_client/NotificationDialog.cs
index ee225de..a824801 100644
--- a/ntfysh_client/NotificationDialog.cs
+++ b/ntfysh_client/NotificationDialog.cs
@@ -5,6 +5,7 @@ using System.Windows.Forms;
 using System.ComponentModel;
 using Microsoft.Win32;
 using System.Diagnostics;
+using ntfysh_client.Themes;
 
 
 namespace ntfysh_client
@@ -21,6 +22,10 @@ namespace ntfysh_client
         private System.Windows.Forms.Timer? _updateTimer = null;
         private Stopwatch? _shownStopwatch = null;
 
+        private BaseTheme _darkModeTheme = new DarkModeTheme();
+        private BaseTheme _defaultTheme = new DefaultTheme();
+        private BaseTheme? _theme = null;
+
         public NotificationDialog()
         {
             ShowInTaskbar = false;
@@ -38,6 +43,17 @@ namespace ntfysh_client
                 HandleTimeout(null, null);
             }
 
+            if(showInDarkMode)
+            {
+                _theme = _darkModeTheme;
+            }
+            else
+            {
+                _theme = _defaultTheme;
+            }
+
+            ApplyTheme();
+
             // setup data
             IconBox.Image = (icon is null) ? null : ConvertToolTipIconToImage(icon.Value);
 
@@ -95,6 +111,31 @@ namespace ntfysh_client
             SetWindowPosition();
         }
 
+        private void ApplyTheme()
+        {
+            if (_theme is null) _theme = _defaultTheme;
+
+            // back colors
+            BackColor = _theme.BackgroundColor;
+            TxBTitle.BackColor = _theme.BackgroundColor;
+            TxBMessage.BackColor = _theme.BackgroundColor;
+            LblTimeout.BackColor = _theme.BackgroundColor;
+            ProgressBar1.BackColor = _theme.BackgroundColor;
+
+            // this one is not "hiding"
+            ButtonClose.BackColor = _theme.ControlBackGroundColor;
+            // handle mouse over
+            ButtonClose.FlatAppearance.MouseOverBackColor = _theme.ControlMouseOverBackgroundColor;
+
+            // fore colors
+            ForeColor = _theme.ForegroundColor;
+            TxBTitle.ForeColor = _theme.ForegroundColor;
+            TxBMessage.ForeColor = _theme.ForegroundColor;
+            LblTimeout.ForeColor = _theme.ForegroundColor;
+            ProgressBar1.ForeColor = _theme.ForegroundColor;
+            ButtonClose.ForeColor = _theme.ForegroundColor;
+        }
+
         private void UpdateProgress(object? sender, EventArgs e)
         {
             if (_shownStopwatch is null) return;
diff --git a/ntfysh_client/Themes/BaseTheme.cs b/ntfysh_client/Themes/BaseTheme.cs
new file mode 100644
index 0000000..b139ab9
--- /dev/null
+++ b/ntfysh_client/Themes/BaseTheme.cs
@@ -0,0 +1,12 @@
+using System.Drawing;
+
+namespace ntfysh_client.Themes
+{
+    internal abstract class BaseTheme
+    {
+        public abstract Color BackgroundColor {get; }
+        public abstract Color ControlBackGroundColor {get; }
+        public abstract Color ControlMouseOverBackgroundColor { get; }
+        public abstract Color ForegroundColor { get; }
+    }
+}
diff --git a/ntfysh_client/Themes/DarkModeTheme.cs b/ntfysh_client/Themes/DarkModeTheme.cs
new file mode 100644
index 0000000..51adc3c
--- /dev/null
+++ b/ntfysh_client/Themes/DarkModeTheme.cs
@@ -0,0 +1,12 @@
+using System.Drawing;
+
+namespace ntfysh_client.Themes
+{
+    internal class DarkModeTheme: BaseTheme
+    {
+        public override Color BackgroundColor { get => SystemColors.ControlDark; }
+        public override Color ControlBackGroundColor { get => Color.Black; }
+        public override Color ControlMouseOverBackgroundColor { get => Color.Silver; }
+        public override Color ForegroundColor { get => SystemColors.ControlLight; }
+    }
+}
diff --git a/ntfysh_client/Themes/DefaultTheme.cs b/ntfysh_client/Themes/DefaultTheme.cs
new file mode 100644
index 0000000..b435a16
--- /dev/null
+++ b/ntfysh_client/Themes/DefaultTheme.cs
@@ -0,0 +1,12 @@
+using System.Drawing;
+
+namespace ntfysh_client.Themes
+{
+    internal class DefaultTheme: BaseTheme
+    {
+        public override Color BackgroundColor { get => Color.White; }
+        public override Color ControlBackGroundColor { get => SystemColors.ControlDark; }
+        public override Color ControlMouseOverBackgroundColor { get => Color.LightSkyBlue; }
+        public override Color ForegroundColor { get => SystemColors.WindowText; }
+    }
+}