Custom backgrounds for light and dark themes

App.xaml

<Application x:Class="MaterialDesignTest.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:MaterialDesignTest"
             xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
             StartupUri="MainWindow.xaml">

    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <materialDesign:BundledTheme BaseTheme="Light" PrimaryColor="DeepPurple" SecondaryColor="Lime" />
                <ResourceDictionary Source="pack://application:,,,/MaterialDesignThemes.Wpf;component/Themes/MaterialDesignTheme.Defaults.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

App.xaml.cs

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Media;
using MaterialDesignColors;
using MaterialDesignThemes.Wpf;

namespace MaterialDesignTest
{
    /// <summary>
    /// Interaction logic for App.xaml
    /// </summary>
    public partial class App : Application
    {
        PaletteHelper PaletteHelper { get; } = new PaletteHelper();
        MaterialDesignLightTheme LightTheme { get; } = new MaterialDesignLightTheme();
        MaterialDesignDarkTheme DarkTheme { get; } = new MaterialDesignDarkTheme();
        public BaseTheme? CurrentTheme { get; set; }

        protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);

            var bundle = Resources
                .MergedDictionaries
                .Where(d => d is BundledTheme)
                .Cast<BundledTheme>()
                .First();

            CurrentTheme = bundle.BaseTheme;
        }

        public void SwitchTheme()
        {
            var isLight = CurrentTheme == BaseTheme.Light;
            var theme = PaletteHelper.GetTheme();
            var baseTheme = isLight ? Theme.Dark : Theme.Light;

            if (isLight)
            {
                theme = new CustomDarkTheme();
            }
            else
            {
                theme = new CustomLightTheme();
            }

            theme.SetBaseTheme(baseTheme);
            PaletteHelper.SetTheme(theme);
            CurrentTheme = isLight ? BaseTheme.Dark : BaseTheme.Light;
        }
    }

    public class CustomDarkTheme : ITheme
    {
        public ColorPair PrimaryLight { get; set; } = Colors.Red;
        public ColorPair PrimaryMid { get; set; } = Colors.Lime;
        public ColorPair PrimaryDark { get; set; } = Colors.Blue;
        public ColorPair SecondaryLight { get; set; } = Colors.Orchid;
        public ColorPair SecondaryMid { get; set; } = Colors.Turquoise;
        public ColorPair SecondaryDark { get; set; } = Colors.Olive;
        public Color ValidationError { get; set; } = Colors.Orange;
        public Color Background { get; set; } = Colors.Salmon;              // Won't work?
        public Color Paper { get; set; } = Colors.SeaGreen;                 // Won't work?
        public Color CardBackground { get; set; } = Colors.SlateGray;       // Won't work?
        public Color ToolBarBackground { get; set; }
        public Color Body { get; set; }
        public Color BodyLight { get; set; }
        public Color ColumnHeader { get; set; }
        public Color CheckBoxOff { get; set; }
        public Color CheckBoxDisabled { get; set; }
        public Color Divider { get; set; }
        public Color Selection { get; set; }
        public Color ToolForeground { get; set; }
        public Color ToolBackground { get; set; }
        public Color FlatButtonClick { get; set; }
        public Color FlatButtonRipple { get; set; }
        public Color ToolTipBackground { get; set; }
        public Color ChipBackground { get; set; }
        public Color SnackbarBackground { get; set; }
        public Color SnackbarMouseOver { get; set; }
        public Color SnackbarRipple { get; set; }
        public Color TextBoxBorder { get; set; }
        public Color TextFieldBoxBackground { get; set; }
        public Color TextFieldBoxHoverBackground { get; set; }
        public Color TextFieldBoxDisabledBackground { get; set; }
        public Color TextAreaBorder { get; set; }
        public Color TextAreaInactiveBorder { get; set; }
        public Color DataGridRowHoverBackground { get; set; }
    }

    public class CustomLightTheme : ITheme
    {
        public ColorPair PrimaryLight { get; set; } = Colors.DarkRed;
        public ColorPair PrimaryMid { get; set; } = Colors.DarkGreen;
        public ColorPair PrimaryDark { get; set; } = Colors.DarkBlue;
        public ColorPair SecondaryLight { get; set; } = Colors.DarkOrchid;
        public ColorPair SecondaryMid { get; set; } = Colors.DarkTurquoise;
        public ColorPair SecondaryDark { get; set; } = Colors.DarkOliveGreen;
        public Color ValidationError { get; set; } = Colors.Orange;
        public Color Background { get; set; } = Colors.DarkSalmon;              // Won't work?
        public Color Paper { get; set; } = Colors.DarkSeaGreen;                 // Won't work?
        public Color CardBackground { get; set; } = Colors.DarkSlateGray;       // Won't work?
        public Color ToolBarBackground { get; set; }
        public Color Body { get; set; }
        public Color BodyLight { get; set; }
        public Color ColumnHeader { get; set; }
        public Color CheckBoxOff { get; set; }
        public Color CheckBoxDisabled { get; set; }
        public Color Divider { get; set; }
        public Color Selection { get; set; }
        public Color ToolForeground { get; set; }
        public Color ToolBackground { get; set; }
        public Color FlatButtonClick { get; set; }
        public Color FlatButtonRipple { get; set; }
        public Color ToolTipBackground { get; set; }
        public Color ChipBackground { get; set; }
        public Color SnackbarBackground { get; set; }
        public Color SnackbarMouseOver { get; set; }
        public Color SnackbarRipple { get; set; }
        public Color TextBoxBorder { get; set; }
        public Color TextFieldBoxBackground { get; set; }
        public Color TextFieldBoxHoverBackground { get; set; }
        public Color TextFieldBoxDisabledBackground { get; set; }
        public Color TextAreaBorder { get; set; }
        public Color TextAreaInactiveBorder { get; set; }
        public Color DataGridRowHoverBackground { get; set; }
    }
}

MainWindow.xaml

<Window x:Class="MaterialDesignTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:MaterialDesignTest"
        xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
        mc:Ignorable="d"
        Background="{DynamicResource MaterialDesignPaper}"
        TextElement.Foreground="{DynamicResource MaterialDesignBody}"
        Title="MainWindow" Height="Auto" Width="500">

    <!--
    https://intellitect.com/getting-started-material-design-in-xaml/
    https://programmer.ink/think/wpf-uses-material-design-to-make-a-beautiful-login-page.html
    
    https://gitter.im/ButchersBoy/MaterialDesignInXamlToolkit
    -->

    <StackPanel Orientation="Vertical">
        <Separator Height="12" Visibility="Hidden" />

        <!-- Change theme and some button -->
        <DockPanel>

            <StackPanel Orientation="Horizontal"
                        Margin="12,0,0,0"
                        DockPanel.Dock="Left"
                        HorizontalAlignment="Left">

                <materialDesign:PackIcon Kind="WhiteBalanceSunny"
                                         Margin="0,0,6,0"
                                         VerticalAlignment="Center"/>

                <ToggleButton Style="{StaticResource MaterialDesignSwitchToggleButton}"
                              Click="ToggleButton_Click"/>

                <materialDesign:PackIcon Kind="MoonWaxingCrescent"
                                         Margin="6,0,0,0"
                                         VerticalAlignment="Center" />
            </StackPanel>

            <Button Style="{DynamicResource MaterialDesignRaisedAccentButton}"
                DockPanel.Dock="Right"
                Padding="20,0"
                Margin="0,0,12,0"
                Click="Button_Click"
                Content="Click"/>

            <Separator Visibility="Hidden" />
        </DockPanel>

        <Separator Height="12" Visibility="Hidden" />

        <materialDesign:Card HorizontalAlignment="Center"
                             VerticalAlignment="Center"
                             Padding="10"  >
            <StackPanel>
                <TextBlock Text="1337 asdf wasd DEADBEEF" />
            </StackPanel>

        </materialDesign:Card>

        <Separator Height="12" Visibility="Hidden" />

        <TextBlock Background="{DynamicResource PrimaryHueLightBrush}"
                   Foreground="{DynamicResource PrimaryHueLightForegroundBrush}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="PrimaryHueLightBrush / PrimaryHueLightForegroundBrush" />

        <TextBlock Background="{DynamicResource PrimaryHueMidBrush}"
                   Foreground="{DynamicResource PrimaryHueMidForegroundBrush}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="PrimaryHueMidBrush / PrimaryHueMidForegroundBrush" />

        <TextBlock Background="{DynamicResource PrimaryHueDarkBrush}"
                   Foreground="{DynamicResource PrimaryHueDarkForegroundBrush}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="PrimaryHueDarkBrush / PrimaryHueDarkForegroundBrush" />

        <TextBlock Background="{DynamicResource SecondaryHueLightBrush}"
                   Foreground="{DynamicResource SecondaryHueLightForegroundBrush}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="SecondaryHueLightBrush / SecondaryHueLightForegroundBrush" />

        <TextBlock Background="{DynamicResource SecondaryHueMidBrush}"
                   Foreground="{DynamicResource SecondaryHueMidForegroundBrush}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="SecondaryHueMidBrush / SecondaryHueMidForegroundBrush" />

        <TextBlock Background="{DynamicResource SecondaryHueDarkBrush}"
                   Foreground="{DynamicResource SecondaryHueDarkForegroundBrush}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="SecondaryHueDarkBrush / SecondaryHueDarkBrush" />

        <TextBlock Background="{DynamicResource MaterialDesignBackground}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="MaterialDesignBackground" />

        <TextBlock Background="{DynamicResource MaterialDesignPaper}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="MaterialDesignPaper" />

        <TextBlock Background="{DynamicResource MaterialDesignCardBackground}"
                   Width="400"
                   Margin="12"
                   TextAlignment="Center"
                   Text="MaterialDesignCardBackground" />

    </StackPanel>
</Window>

MianWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using MaterialDesignThemes.Wpf;

namespace MaterialDesignTest
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("Nothing");
        }

        private void ToggleButton_Click(object sender, RoutedEventArgs e)
        {
            var app = Application.Current as App;
            app.SwitchTheme();
        }
    }
}