MyUserControl.xaml

<UserControl x:Class="SO_75067133.MyUserControl"
             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" 
             d:DesignHeight="450" d:DesignWidth="800">

    <Grid Background="Blue"
          Margin="10">
        <Grid Background="white"
              Margin="10">
            <Grid Background="Red"
                  Margin="10">
                <Grid Background="White"
                      Margin="10"
                      MinHeight="150"
                      MinWidth="150">
                    <Label x:Name="Label"
                           Content="Not Loaded"
                           HorizontalAlignment="Center"
                           VerticalAlignment="Center" />
                </Grid>
            </Grid>
        </Grid>
    </Grid>
</UserControl>