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You can omit defining the TargetType of a Style, but, for that to work, you must define the property with a fully qualified name. For example, the preceding Style can be written as shown here to get the same result:

<Style x:Key="ButtonBaseStyle"> 
    <Setter Property="Button.Height"  
            Value="30"/> 
    <Setter Property="Button.MinWidth"  
            Value="180"/> 
    <Setter Property="Button.FontSize"  
            Value="16"/> 
    <Setter Property="Button.HorizontalAlignment"  
            Value="Center"/> 
    <Setter Property="Button.Padding"  
            Value="8 0"/> 
    <Setter Property="Button.Margin"  
            Value="4"/> 
    <Setter Property="Button.Cursor"  
            Value="Hand"/> 
    <Setter Property="Button.BorderThickness...