Add missing FontFamily to the EmbeddableControlRoot

src/Avalonia.Themes.Fluent/Controls/EmbeddableControlRoot.xaml

@@ -4,6 +4,7 @@
     <Setter Property="Foreground" Value="{DynamicResource SystemControlForegroundBaseHighBrush}"/>
     <Setter Property="Background" Value="{DynamicResource SystemControlBackgroundAltHighBrush}"/>
     <Setter Property="FontSize" Value="{DynamicResource ControlContentThemeFontSize}"/>
+    <Setter Property="FontFamily" Value="{DynamicResource ContentControlThemeFontFamily}" />
     <Setter Property="Template">
       <ControlTemplate>
         <Panel>