styling-summary-rows-in-wpf-datagrid

The appearance of WPF DataGrid and its inner elements (example: Cell, Row, Header, Summary etc.) can be customized using various properties exposed and by editing the elements’ Style.

<Window.Resources>
    <!--Table summary cell style-->
    <Style TargetType="syncfusion:GridTableSummaryCell">
        <Setter Property="Background" Value="Beige"/>
        <Setter Property="Foreground" Value="Red" />
        <Setter Property="FontSize" Value="16" />
        <Setter Property="FontFamily" Value="Congenial Black"/>
        <Setter Property="FontWeight" Value="Bold" />
    </Style>
    <Style TargetType="syncfusion:TableSummaryRowControl">
        <Setter Property="Background" Value="Bisque"/>
        <Setter Property="FontStyle" Value="Italic"/>
        <Setter Property="Foreground" Value="Red"/>
    </Style>
    
    <!--Group summary cell style-->
    <Style TargetType="syncfusion:GridGroupSummaryCell">
        <Setter Property="Background" Value="Beige"/>
        <Setter Property="FontWeight" Value="SemiBold"/>
        <Setter Property="Foreground" Value="DarkBlue"/>
        <Setter Property="FontStyle" Value="Oblique"/>
        <Setter Property="FontFamily" Value="Congenial Black"/>
        <Setter Property="FontSize" Value="14"/>
    </Style>
    
    <!--Group summary row style-->
    <Style TargetType="syncfusion:GroupSummaryRowControl">
        <Setter Property="Background" Value="Bisque"/>
    </Style>
    
    <!--Caption summary cell style-->
    <Style TargetType="syncfusion:GridCaptionSummaryCell">
        <Setter Property="Background" Value="Beige"/>
        <Setter Property="FontWeight" Value="Bold"/>
        <Setter Property="Foreground" Value="DarkBlue"/>
        <Setter Property="FontStyle" Value="Italic"/>
        <Setter Property="FontFamily" Value="Congenial Black"/>
        <Setter Property="FontSize" Value="14"/>
    </Style>

    <Style TargetType="syncfusion:CaptionSummaryRowControl"
           x:Key="captionSummaryRowStyle">
        <Setter Property="Background" Value="Bisque"/>
    </Style>
</Window.Resources>

Take a moment to peruse the WPF DataGrid - Styling documentation, to learn more about styles & templates code examples.