<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
                    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                    mc:Ignorable="d">


    <Style TargetType="{x:Type Sidebar}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Sidebar}">
                    <Border Background="Yellow"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}"
                            d:DesignWidth="64" d:DesignHeight="400"
                            d:DataContext="{x:Static DesignMainViewModel.DesignIntance}">
                        <TextBlock Text="Sidebar" />
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>