FontSize is now amendable in DataGrid...

...however, the column header font size is specified differently (as per the material design spec).  So to change the column header style a custom DataGridColumnHeader must be applied.

Fixes #168

Author: ButchersBoy

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.DataGrid.xaml

@@ -147,7 +147,7 @@
     </Style>
 
     <Style x:Key="MaterialDesignDataGridCell" TargetType="{x:Type DataGridCell}">
-        <Setter Property="TextBlock.FontSize" Value="13" />
+        <!--Setter Property="TextBlock.FontSize" Value="13" /-->
         <Setter Property="Padding" Value="{Binding RelativeSource={RelativeSource Self}, Path=(wpf:DataGridAssist.CellPadding)}" />
         <Setter Property="Background" Value="Transparent"/>
         <Setter Property="BorderBrush" Value="Transparent"/>
@@ -342,6 +342,7 @@
         <Setter Property="Foreground" Value="{DynamicResource MaterialDesignBody}"/>
         <Setter Property="BorderBrush" Value="{DynamicResource MaterialDesignTextBoxBorder}"/>
         <Setter Property="BorderThickness" Value="0"/>
+        <Setter Property="FontSize" Value="13"/>
         <Setter Property="GridLinesVisibility" Value="Horizontal" />
         <Setter Property="RowDetailsVisibilityMode" Value="VisibleWhenSelected"/>
         <Setter Property="HeadersVisibility" Value="Column" />