✅ Styling Expander Avalonia

<Style Selector="Expander">
        <!-- changes styles of content inside drop down -->
    <Setter Property="BorderBrush" Value="{DynamicResource ResourceKey=DarkGray}" />
    <Setter Property="Background" Value="{DynamicResource ResourceKey=Purple}" />
    <Setter Property="Foreground" Value="{DynamicResource ResourceKey=Pink}" />
    <Setter Property="FontSize" Value="20" />
    <Setter Property="FontWeight" Value="Bold" />
    <Setter Property="Width" Value="1200" />
    <Setter Property="HorizontalAlignment" Value="Center" />
    <Setter Property="VerticalAlignment" Value="Center" />
    <Setter Property="Margin" Value="0,20,0,0" />
    <Setter Property="BorderThickness" Value="2" />
    <Setter Property="CornerRadius" Value="20" />

        <!-- changes styles of header -->
    <Style Selector="^ /template/ ToggleButton#ExpanderHeader">
        <Setter Property="Background" Value="{DynamicResource ResourceKey=Purple}" />
        <Setter Property="Foreground" Value="{DynamicResource ResourceKey=Pink}" />
    </Style>
</Style>