ZonyLrcToolsX/src/ZonyLrcTools.Desktop/Views/MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="using:ZonyLrcTools.Desktop.ViewModels"
        xmlns:pages="using:ZonyLrcTools.Desktop.Views.Pages"
        xmlns:loc="using:ZonyLrcTools.Desktop.Infrastructure.Localization"
        x:Class="ZonyLrcTools.Desktop.Views.MainWindow"
        x:DataType="vm:MainWindowViewModel"
        Title="{Binding Title}"
        Width="1200" Height="800"
        MinWidth="900" MinHeight="600"
        WindowStartupLocation="CenterScreen">

    <Window.Styles>
        <!-- Nav ListBoxItem: remove default selection background, use rounded style -->
        <Style Selector="ListBox.nav-list ListBoxItem">
            <Setter Property="Padding" Value="12,10" />
            <Setter Property="Margin" Value="8,2" />
            <Setter Property="CornerRadius" Value="6" />
            <Setter Property="Background" Value="Transparent" />
        </Style>
        <Style Selector="ListBox.nav-list ListBoxItem:selected /template/ ContentPresenter">
            <Setter Property="Background" Value="{DynamicResource NavActiveBackgroundBrush}" />
        </Style>
        <Style Selector="ListBox.nav-list ListBoxItem:pointerover /template/ ContentPresenter">
            <Setter Property="Background" Value="{DynamicResource NavActiveBackgroundBrush}" />
            <Setter Property="Opacity" Value="0.6" />
        </Style>
        <Style Selector="ListBox.nav-list ListBoxItem:selected:pointerover /template/ ContentPresenter">
            <Setter Property="Opacity" Value="1" />
        </Style>
        <Style Selector="ListBox.nav-list">
            <Setter Property="Background" Value="Transparent" />
        </Style>
    </Window.Styles>

    <Grid ColumnDefinitions="240,*">
        <!-- Left Navigation Panel -->
        <Border Grid.Column="0"
                Background="{DynamicResource NavigationBackgroundBrush}"
                BorderBrush="{DynamicResource SeparatorBrush}"
                BorderThickness="0,0,1,0">
            <DockPanel Margin="0,8,0,0">
                <!-- Logo Area -->
                <StackPanel DockPanel.Dock="Top" Margin="24,16,24,24">
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="ZonyLrcTools"
                                   FontSize="20"
                                   FontWeight="Bold"
                                   VerticalAlignment="Center" />
                        <Border Background="#000000"
                                CornerRadius="4"
                                Padding="5,1"
                                Margin="3,0,0,0"
                                VerticalAlignment="Center">
                            <TextBlock Text="X"
                                       FontSize="12"
                                       FontWeight="Bold"
                                       Foreground="White" />
                        </Border>
                    </StackPanel>
                    <TextBlock Text="{Binding HomeDescription}"
                               FontSize="12"
                               Opacity="0.5"
                               Margin="0,4,0,0" />
                </StackPanel>

                <!-- Theme Toggle (bottom) -->
                <Border DockPanel.Dock="Bottom"
                        Background="{DynamicResource ContentAreaBrush}"
                        CornerRadius="6"
                        Margin="16,0,16,16"
                        Padding="12,8">
                    <Button Command="{Binding ToggleThemeCommand}"
                            HorizontalAlignment="Center"
                            Background="Transparent"
                            BorderThickness="0"
                            Padding="0">
                        <StackPanel Orientation="Horizontal" Spacing="8">
                            <PathIcon Data="{StaticResource MoonIcon}"
                                      Width="14" Height="14"
                                      IsVisible="{Binding !IsDarkTheme}" />
                            <PathIcon Data="{StaticResource SunIcon}"
                                      Width="14" Height="14"
                                      IsVisible="{Binding IsDarkTheme}" />
                            <TextBlock Text="{Binding ThemeButtonText}"
                                       VerticalAlignment="Center"
                                       FontSize="13" />
                        </StackPanel>
                    </Button>
                </Border>

                <!-- Navigation Menu -->
                <ListBox Classes="nav-list"
                         SelectedIndex="{Binding SelectedNavigationIndex}"
                         Margin="0,8,0,0"
                         SelectionChanged="OnNavigationSelectionChanged">
                    <ListBoxItem>
                        <StackPanel Orientation="Horizontal" Spacing="8">
                            <Border Width="3" CornerRadius="1.5"
                                    Background="{DynamicResource AppAccentBrush}"
                                    Margin="0,2"
                                    IsVisible="{Binding $parent[ListBoxItem].IsSelected}" />
                            <PathIcon Data="{StaticResource HomeIcon}"
                                      Width="16" Height="16" />
                            <TextBlock Text="{Binding NavHome}"
                                       VerticalAlignment="Center" />
                        </StackPanel>
                    </ListBoxItem>
                    <ListBoxItem>
                        <StackPanel Orientation="Horizontal" Spacing="8">
                            <Border Width="3" CornerRadius="1.5"
                                    Background="{DynamicResource AppAccentBrush}"
                                    Margin="0,2"
                                    IsVisible="{Binding $parent[ListBoxItem].IsSelected}" />
                            <PathIcon Data="{StaticResource MusicNoteIcon}"
                                      Width="16" Height="16" />
                            <TextBlock Text="{Binding NavLyricsDownload}"
                                       VerticalAlignment="Center" />
                        </StackPanel>
                    </ListBoxItem>
                    <ListBoxItem>
                        <StackPanel Orientation="Horizontal" Spacing="8">
                            <Border Width="3" CornerRadius="1.5"
                                    Background="{DynamicResource AppAccentBrush}"
                                    Margin="0,2"
                                    IsVisible="{Binding $parent[ListBoxItem].IsSelected}" />
                            <PathIcon Data="{StaticResource ImageIcon}"
                                      Width="16" Height="16" />
                            <TextBlock Text="{Binding NavAlbumDownload}"
                                       VerticalAlignment="Center" />
                        </StackPanel>
                    </ListBoxItem>
                    <ListBoxItem>
                        <StackPanel Orientation="Horizontal" Spacing="8">
                            <Border Width="3" CornerRadius="1.5"
                                    Background="{DynamicResource AppAccentBrush}"
                                    Margin="0,2"
                                    IsVisible="{Binding $parent[ListBoxItem].IsSelected}" />
                            <PathIcon Data="{StaticResource SettingsIcon}"
                                      Width="16" Height="16" />
                            <TextBlock Text="{Binding NavSettings}"
                                       VerticalAlignment="Center" />
                        </StackPanel>
                    </ListBoxItem>
                </ListBox>
            </DockPanel>
        </Border>

        <!-- Right Content Area -->
        <Border Grid.Column="1"
                Background="{DynamicResource ContentAreaBrush}"
                Padding="24">
            <ContentControl Content="{Binding CurrentPage}">
                <ContentControl.DataTemplates>
                    <DataTemplate DataType="vm:HomeViewModel">
                        <pages:HomePage />
                    </DataTemplate>
                    <DataTemplate DataType="vm:LyricsDownloadViewModel">
                        <pages:LyricsDownloadPage />
                    </DataTemplate>
                    <DataTemplate DataType="vm:AlbumDownloadViewModel">
                        <pages:AlbumDownloadPage />
                    </DataTemplate>
                    <DataTemplate DataType="vm:SettingsViewModel">
                        <pages:SettingsPage />
                    </DataTemplate>
                </ContentControl.DataTemplates>
            </ContentControl>
        </Border>
    </Grid>

</Window>