how to change the color of drop down button of combo box in wpf

<Style TargetType="{x:Type ComboBoxItem}">
            <Setter Property="Background">
                <Setter.Value>
                    <LinearGradientBrush EndPoint="0,1" StartPoint="0,0">
                        <GradientStop Color="#FF3A60AD" Offset="0.528"/>
                        <GradientStop Color="#FF6A85D8" Offset="0.01"/>
                        <GradientStop Color="#FF3464C4" Offset="1"/>
                        <GradientStop Color="#FF202E7E" Offset="1"/>
                    </LinearGradientBrush>
                </Setter.Value>
            </Setter>
        </Style>

 
You can add a style to target All comboBox Item, which is what is given in my example. Alternatively, you can individually brush each item by modifying each items individual properties.