Change background color on mouseover
<p>I've managed to make a rounded border button, but I cannot seem to change its background color when the mouse is over. The opacity changes, but not the background color.</p>

<pre><code>&lt;Style TargetType="Button" x:Key="FlatButtonStyle"&gt;
    &lt;Setter Property="OverridesDefaultStyle" Value="True" /&gt;
    &lt;Setter Property="Cursor" Value="Hand" /&gt;
    &lt;Setter Property="Template"&gt;
        &lt;Setter.Value&gt;
            &lt;ControlTemplate TargetType="{x:Type Button}"&gt;
                &lt;Border Name="border" BorderThickness="0" BorderBrush="Black" Background="{TemplateBinding Background}" CornerRadius="4"&gt;
                    &lt;ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" /&gt;
                &lt;/Border&gt;

            &lt;/ControlTemplate&gt;
        &lt;/Setter.Value&gt;
    &lt;/Setter&gt;
    &lt;Style.Triggers&gt;
        &lt;Trigger Property="IsMouseOver" Value="True"&gt;
            &lt;Setter Property="Background" Value="Orange"/&gt;
            &lt;Setter Property="Opacity" Value="0.91" /&gt;

        &lt;/Trigger&gt;
    &lt;/Style.Triggers&gt;
&lt;/Style&gt;
</code></pre>

<p>As you can see, I'm not sure why opacity works but not the other. However, I think it's a conflict with the actual button itself:</p>

<pre><code>&lt;Button Style="{StaticResource FlatButtonStyle}" Content="Sign In" VerticalAlignment="Top" Margin="10,267,10,0" Background="#FF3650F3" Foreground="White" Height="29" Command="{Binding SignIn}"&gt;
</code></pre>

<p>Is there a way to override this? What I'm looking to do is create a generic, rounded button template that changes the background to orange. But I want the ability to set a default background, like I have shown in my button.</p>