Button's nested style trigger not executed after click - wpf

Question

I've tried to recreate a material design kind of button. One of the animations of this button is that upon mouse over is that the color of the button changes to a darker hue of the original color.
In order to realise this for every color, I overlay my button with a rectangle and change it's opacity between 25 % and 0 % depending on mouse over or not. This style is implemented in the style of the rectangle. But it appears that this style is only executed before I click. Once I click the button, this style trigger is not executed anymore.
I've also implemented a animation to change the opacity of the rectangle to 40 % when the button is clicked. this animation however, is still visible after the first click.
I thought that it might be because the rectangle's style is included in the control template. But I don't know how to extract those styles from the control template to the button's style.
<Style x:Key="MaterialFlatButton" TargetType="Button">
<Setter Property="Foreground" Value="Black"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Grid>
<Rectangle RadiusX="4" RadiusY="4" Fill="#000000" Panel.ZIndex="1" x:Name="Reccie">
<Rectangle.Style>
<Style TargetType="{x:Type Rectangle}">
<Setter Property="Opacity" Value="0"/>
<!--These styles-->
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Opacity" Value="0.26"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="false">
<Setter Property="Opacity" Value="0"/>
</Trigger>
<EventTrigger RoutedEvent="MouseLeftButtonDown">
<BeginStoryboard>
<Storyboard>
<DoubleAnimation Storyboard.TargetProperty="Opacity" To="0.4" Duration="0:0:0.25"/>
<DoubleAnimation Storyboard.TargetProperty="Opacity" To="0" Duration="0:0:0.25" />
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Style.Triggers>
</Style>
</Rectangle.Style>
</Rectangle>
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"
Margin="16 0 16 0" TextBlock.FontFamily="{StaticResource LatoMedium}"
TextBlock.FontSize="{StaticResource FontSizeBody}" Typography.Capitals="AllSmallCaps"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<!--Should go here perhaps?-->
<Style.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="#000000"/>
<Setter Property="Opacity" Value="0.26"/>
</Trigger>
</Style.Triggers>
</Style>

Answer 1

edit: does it do what you want if you set FillBehavior="Stop"?
<EventTrigger RoutedEvent="MouseLeftButtonDown">
<BeginStoryboard>
<Storyboard FillBehavior="Stop">
<DoubleAnimation Storyboard.TargetProperty="Opacity" From="0.26" To="0.4" Duration="0:0:0.25"/>
</Storyboard>
</BeginStoryboard>
</EventTrigger>