Semi.Avalonia/src/Semi.Avalonia/Controls/EmbeddableControlRoot.axaml

<ResourceDictionary xmlns="https://github.com/avaloniaui" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <ControlTheme x:Key="{x:Type EmbeddableControlRoot}" TargetType="EmbeddableControlRoot">
        <Setter Property="Background" Value="{DynamicResource WindowDefaultBackground}" />
        <Setter Property="Foreground" Value="{DynamicResource WindowDefaultForeground}" />
        <Setter Property="FontSize" Value="{DynamicResource DefaultFontSize}" />
        <Setter Property="FontFamily" Value="{DynamicResource DefaultFontFamily}" />
        <Setter Property="Template">
            <ControlTemplate>
                <Panel>
                    <Border Name="PART_TransparencyFallback" IsHitTestVisible="False" />
                    <Border Background="{TemplateBinding Background}">
                        <VisualLayerManager>
                            <ContentPresenter
                                Name="PART_ContentPresenter"
                                Margin="{TemplateBinding Padding}"
                                Content="{TemplateBinding Content}"
                                ContentTemplate="{TemplateBinding ContentTemplate}" />
                        </VisualLayerManager>
                    </Border>
                </Panel>
            </ControlTemplate>
        </Setter>
    </ControlTheme>
</ResourceDictionary>