Theme

App.xaml

<Application x:Class="WpfThemeApp.App"

             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

             xmlns:local="clr-namespace:WpfThemeApp"

             StartupUri="MainWindow.xaml">

    <Application.Resources>

        <ResourceDictionary>

            <ResourceDictionary.MergedDictionaries>

                <ResourceDictionary Source="/Theme/BlueTheme.xaml" />

            </ResourceDictionary.MergedDictionaries>

        </ResourceDictionary>

    </Application.Resources>

</Application>

Resource File

    <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

        <!-- Color Palette -->

        <Color x:Key="PrimaryBlueColor">#FF1565C0</Color>

        <Color x:Key="SecondaryBlueColor">#FF1E88E5</Color>

        <Color x:Key="AccentBlueColor">#FF64B5F6</Color>

        <Color x:Key="LightBlueColor">#FFBBDEFB</Color>

        <Color x:Key="DarkBlueColor">#FF0D47A1</Color>

        <Color x:Key="DangerColor">#FF3F34</Color>

    <!-- Brushes -->

        <SolidColorBrush x:Key="PrimaryBlueBrush" Color="{StaticResource PrimaryBlueColor}" />

        <SolidColorBrush x:Key="SecondaryBlueBrush" Color="{StaticResource SecondaryBlueColor}" />

        <SolidColorBrush x:Key="AccentBlueBrush" Color="{StaticResource AccentBlueColor}" />

        <SolidColorBrush x:Key="LightBlueBrush" Color="{StaticResource LightBlueColor}" />

        <SolidColorBrush x:Key="DarkBlueBrush" Color="{StaticResource DarkBlueColor}" />

        <SolidColorBrush x:Key="TextOnBlueBrush" Color="White" />

        <SolidColorBrush x:Key="OrangeRedBrush" Color="{StaticResource DangerColor}"/>

    <!-- Window Background -->

        <Style TargetType="Window">

            <Setter Property="Background" Value="{StaticResource LightBlueBrush}" />

            <Setter Property="Foreground" Value="{StaticResource DarkBlueBrush}" />

        </Style>

        <!-- Button Style -->

        <Style TargetType="Button">

            <Setter Property="Background" Value="{StaticResource PrimaryBlueBrush}" />

            <Setter Property="Foreground" Value="{StaticResource TextOnBlueBrush}" />

            <Setter Property="Padding" Value="8,4" />

            <Setter Property="Margin" Value="4" />

            <Setter Property="BorderThickness" Value="0" />

            <Setter Property="FontWeight" Value="Bold" />

            <Setter Property="Template">

                <Setter.Value>

                    <ControlTemplate TargetType="Button">

                        <Border Background="{TemplateBinding Background}"

                            CornerRadius="4">

                            <ContentPresenter HorizontalAlignment="Center"

                                          VerticalAlignment="Center"/>

                        </Border>

                        <ControlTemplate.Triggers>

                            <Trigger Property="IsMouseOver" Value="True">

                                <Setter Property="Background" Value="{StaticResource SecondaryBlueBrush}" />

                            </Trigger>

                            <Trigger Property="IsPressed" Value="True">

                                <Setter Property="Background" Value="{StaticResource DarkBlueBrush}" />

                            </Trigger>

                        </ControlTemplate.Triggers>

                    </ControlTemplate>

                </Setter.Value>

            </Setter>

        </Style>

        <!-- TextBox Style -->

        <Style TargetType="TextBox">

            <Setter Property="Background" Value="White" />

            <Setter Property="Foreground" Value="{StaticResource DarkBlueBrush}" />

            <Setter Property="BorderBrush" Value="{StaticResource PrimaryBlueBrush}" />

            <Setter Property="BorderThickness" Value="1" />

            <Setter Property="Padding" Value="4" />

            <Setter Property="Margin" Value="4" />

            <Setter Property="CaretBrush" Value="{StaticResource PrimaryBlueBrush}" />

        </Style>

        <!-- Label Style -->

        <Style TargetType="Label">

            <Setter Property="Foreground" Value="{StaticResource DarkBlueBrush}" />

            <Setter Property="FontWeight" Value="SemiBold" />

            <Setter Property="Margin" Value="2" />

        </Style>

        <!-- DataGrid Style -->

        <Style TargetType="DataGrid">

            <Setter Property="Background" Value="{StaticResource LightBlueBrush}" />

            <Setter Property="Foreground" Value="{StaticResource DarkBlueBrush}" />

            <Setter Property="BorderBrush" Value="{StaticResource PrimaryBlueBrush}" />

            <Setter Property="RowBackground" Value="White" />

            <Setter Property="AlternatingRowBackground" Value="{StaticResource LightBlueBrush}" />

            <Setter Property="HorizontalGridLinesBrush" Value="{StaticResource AccentBlueBrush}" />

            <Setter Property="VerticalGridLinesBrush" Value="{StaticResource AccentBlueBrush}" />

        </Style>

        <!-- DataGridColumnHeader Style -->

        <Style TargetType="DataGridColumnHeader">

            <Setter Property="Background" Value="{StaticResource PrimaryBlueBrush}" />

            <Setter Property="Foreground" Value="White" />

            <Setter Property="FontWeight" Value="Bold" />

            <Setter Property="Padding" Value="6" />

            <Setter Property="BorderBrush" Value="{StaticResource DarkBlueBrush}" />

            <Setter Property="BorderThickness" Value="0,0,1,1" />

        </Style>

        <!-- ListView Style -->

        <Style TargetType="ListView">

            <Setter Property="Background" Value="White" />

            <Setter Property="Foreground" Value="{StaticResource DarkBlueBrush}" />

            <Setter Property="BorderBrush" Value="{StaticResource PrimaryBlueBrush}" />

            <Setter Property="BorderThickness" Value="1" />

        </Style>

        <!-- ListViewItem Style -->

        <Style TargetType="ListViewItem">

            <Setter Property="Padding" Value="6" />

            <Setter Property="Margin" Value="2" />

            <Setter Property="Background" Value="White" />

            <Setter Property="Foreground" Value="{StaticResource DarkBlueBrush}" />

            <Setter Property="BorderBrush" Value="{StaticResource LightBlueBrush}" />

            <Setter Property="BorderThickness" Value="0,0,0,1" />

            <Setter Property="Template">

                <Setter.Value>

                    <ControlTemplate TargetType="ListViewItem">

                        <Border Background="{TemplateBinding Background}"

                            BorderBrush="{TemplateBinding BorderBrush}"

                            BorderThickness="{TemplateBinding BorderThickness}">

                            <ContentPresenter HorizontalAlignment="Left"

                                          VerticalAlignment="Center"

                                          Margin="{TemplateBinding Padding}" />

                        </Border>

                        <ControlTemplate.Triggers>

                            <Trigger Property="IsMouseOver" Value="True">

                                <Setter Property="Background" Value="{StaticResource LightBlueBrush}" />

                            </Trigger>

                            <Trigger Property="IsSelected" Value="True">

                                <Setter Property="Background" Value="{StaticResource SecondaryBlueBrush}" />

                                <Setter Property="Foreground" Value="White" />

                            </Trigger>

                        </ControlTemplate.Triggers>

                    </ControlTemplate>

                </Setter.Value>

            </Setter>

        </Style>

        <!-- Custom DeleteToAdd Button Style -->

        <Style x:Key="CustomDeleteButton" TargetType="Button">

            <Setter Property="Background" Value="#FF6347"/>

            <!-- Tomato Red -->

            <Setter Property="Foreground" Value="White"/>

            <Setter Property="FontWeight" Value="Bold"/>

            <Setter Property="Padding" Value="8,4"/>

            <Setter Property="BorderBrush" Value="#B22222"/>

            <!-- Firebrick -->

            <Setter Property="BorderThickness" Value="1"/>

            <Setter Property="Template">

                <Setter.Value>

                    <ControlTemplate TargetType="Button">

                        <Border Background="{TemplateBinding Background}"

                            BorderBrush="{TemplateBinding BorderBrush}"

                            BorderThickness="{TemplateBinding BorderThickness}"

                            CornerRadius="4">

                            <ContentPresenter HorizontalAlignment="Center"

                                          VerticalAlignment="Center"/>

                        </Border>

                        <ControlTemplate.Triggers>

                            <!-- Hover -->

                            <Trigger Property="IsMouseOver" Value="True">

                                <Setter Property="Background" Value="#DC143C"/>

                                <!-- Crimson -->

                                <Setter Property="BorderBrush" Value="#8B0000"/>

                                <!-- DarkRed -->

                            </Trigger>

                            <!-- Pressed -->

                            <Trigger Property="IsPressed" Value="True">

                                <Setter Property="Background" Value="#B22222"/>

                                <!-- Firebrick -->

                                <Setter Property="BorderBrush" Value="#800000"/>

                                <!-- Maroon -->

                            </Trigger>

                            <!-- Disabled -->

                            <Trigger Property="IsEnabled" Value="False">

                                <Setter Property="Background" Value="#FFC0CB"/>

                                <!-- Light Pink -->

                                <Setter Property="Foreground" Value="Gray"/>

                            </Trigger>

                        </ControlTemplate.Triggers>

                    </ControlTemplate>

                </Setter.Value>

            </Setter>

        </Style>

</ResourceDictionary>