feat: add default Theme to SplashWindow.

demo/Ursa.Demo/Views/MainSplashWindow.axaml

@@ -2,22 +2,11 @@
     x:Class="Ursa.Demo.Views.MainSplashWindow"
     xmlns="https://github.com/avaloniaui"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:iri="https://irihi.tech/shared"
-    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:u="https://irihi.tech/ursa"
     Title="MainSplashWindow"
     Width="400"
-    Height="400"
-    d:DesignHeight="450"
-    d:DesignWidth="800"
-    CountDown="0:0:3"
-    ExtendClientAreaChromeHints="NoChrome"
-    ExtendClientAreaTitleBarHeightHint="0"
-    ExtendClientAreaToDecorationsHint="True"
-    SystemDecorations="None"
-    WindowStartupLocation="CenterScreen"
-    mc:Ignorable="d">
+    Height="400">
     <Grid
         HorizontalAlignment="Center"
         VerticalAlignment="Center"
@@ -51,4 +40,4 @@
                 Text="Aesthetic Evolution of Productivity" />
         </StackPanel>
     </Grid>
-</u:SplashWindow>
+</u:SplashWindow>

src/Ursa.Themes.Semi/Controls/SplashWindow.axaml

@@ -0,0 +1,27 @@
+<ResourceDictionary
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:u="https://irihi.tech/ursa">
+    <ControlTheme x:Key="{x:Type u:SplashWindow}" TargetType="u:SplashWindow">
+        <Setter Property="CountDown" Value="0:0:3" />
+        <Setter Property="Background" Value="{DynamicResource WindowDefaultBackground}" />
+        <Setter Property="TransparencyBackgroundFallback" Value="{DynamicResource WindowDefaultBackground}" />
+        <Setter Property="Foreground" Value="{DynamicResource WindowDefaultForeground}" />
+        <Setter Property="FontSize" Value="{DynamicResource DefaultFontSize}" />
+        <Setter Property="FontFamily" Value="{DynamicResource DefaultFontFamily}" />
+        <Setter Property="ExtendClientAreaChromeHints" Value="NoChrome" />
+        <Setter Property="ExtendClientAreaTitleBarHeightHint" Value="0" />
+        <Setter Property="ExtendClientAreaToDecorationsHint" Value="True" />
+        <Setter Property="WindowStartupLocation" Value="CenterScreen" />
+        <Setter Property="SystemDecorations">
+            <OnPlatform>
+                <On Options="Default, Windows, macOS">
+                    <SystemDecorations>Full</SystemDecorations>
+                </On>
+                <On Options="Linux">
+                    <SystemDecorations>None</SystemDecorations>
+                </On>
+            </OnPlatform>
+        </Setter>
+    </ControlTheme>
+</ResourceDictionary>

src/Ursa.Themes.Semi/Controls/_index.axaml

@@ -56,5 +56,6 @@
         <ResourceInclude Source="UrsaWindow.axaml"/>
         <ResourceInclude Source="PinCode.axaml" />
         <ResourceInclude Source="PathPicker.axaml"/>
+        <ResourceInclude Source="SplashWindow.axaml"/>
     </ResourceDictionary.MergedDictionaries>
 </ResourceDictionary>

src/Ursa/Windows/SplashWindow.cs

@@ -8,6 +8,8 @@ namespace Ursa.Controls;
 
 public abstract class SplashWindow: Window
 {
+    protected override Type StyleKeyOverride => typeof(SplashWindow);
+
     public static readonly StyledProperty<TimeSpan?> CountDownProperty = AvaloniaProperty.Register<SplashWindow, TimeSpan?>(
         nameof(CountDown));