PDFOffice_Windows_exe/PDF Office/Themes/Generic.xaml

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:cus="clr-namespace:PDF_Office.CustomControl"
    xmlns:local="clr-namespace:PDF_Office">

    <!--  style for customControl  -->
    <Style TargetType="{x:Type cus:DialogContent}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type cus:DialogContent}">
                    <Border Background="White" CornerRadius="8">
                        <Grid Background="Transparent">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="48" />
                                <RowDefinition Height="*" />
                                <RowDefinition Height="64" />
                            </Grid.RowDefinitions>
                            <Border Background="Transparent" BorderThickness="0,0,0,1">
                                <Border.BorderBrush>
                                    <SolidColorBrush Opacity="0.2" Color="Gray" />
                                </Border.BorderBrush>
                                <TextBlock
                                    Margin="16,0,0,0"
                                    VerticalAlignment="Center"
                                    FontSize="16"
                                    FontWeight="SemiBold"
                                    Text="{TemplateBinding Header}" />
                            </Border>
                            <ContentPresenter Grid.Row="1" Content="{TemplateBinding Content}" />
                            <Border Grid.Row="2" BorderThickness="0,1,0,0">
                                <Border.BorderBrush>
                                    <SolidColorBrush Opacity="0.2" Color="Gray" />
                                </Border.BorderBrush>
                                <ContentControl Content="{TemplateBinding BottmBar}" />
                            </Border>
                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>