Hi David,
Sorry for the being caused.
We have done a simple sample, which can be downloaded from the below location.
In the sample we have added the ResourceDictionary, and added the BasedOn property to override the Syncfusion Themes.
CodeSnippet:
ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Syncfusion.Shared.WPF;component/SkinManager/MetroStyle.xaml"/>
</ResourceDictionary.MergedDictionaries>
<Style TargetType="Label" BasedOn="{StaticResource MetroLabelStyle}">
<Setter Property="HorizontalContentAlignment" Value="Right"/>
<Setter Property="Background" Value="Bisque"/>
</Style>
Kindly revert back to us if this sample helps you.
Regards,
Karuppasamy P
StyleDemo_d2d453da.zip