How could I overwrite this DataGrid style property in MaterialDesignThemes?

Question

I'm using material design in XAML, I have a DataGrid, and when a row is selected and the mouse leaves the row then the row's background changes to white, if the mouse returns it changes back to the original color. I think I have found the part of the code that sets it but I don't seem to be able to overwrite it... This is in the 'MaterialDesignDataGridCell' style and to me it seems this sets it.

<MultiDataTrigger>
            <MultiDataTrigger.Conditions>
                <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="True"/>
                <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource AncestorType=DataGridRow}}" Value="False" />
            </MultiDataTrigger.Conditions>
            <Setter Property="Background" Value="{DynamicResource MaterialDesignSelection}" />
        </MultiDataTrigger>

I tried copying this trigger and setting a different value, setting up a trigger just when the mouseover is false to set the background, and tried setting these with no luck :

<Style.Resources>
                        <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Black" />
                        <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="Black" />
                        <SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="Black"/>
                    </Style.Resources>

Answer 1

Not really sure what you are trying to achieve but if you want to override the cell style for your datagrid cells you can do like this

<DataGrid>
   <DataGrid.CellStyle>
        <Style TargetType="DataGridCell" BasedOn="{StaticResource MaterialDesignDataGridCell}">
        <Style.Triggers>
                 <MultiDataTrigger>
                      <MultiDataTrigger.Conditions>
                           <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="True"/>
                           <Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource AncestorType=DataGridRow}}" Value="False" />
                      </MultiDataTrigger.Conditions>
                          <Setter Property="Background" Value="Red" />
                 </MultiDataTrigger>
        </Style.Triggers>
      </Style>
   </DataGrid.CellStyle>
</DataGrid>