probniyDE/MainWindow.xaml

<Window x:Class="Khaustov_ProbniyDE.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Khaustov_ProbniyDE"
        mc:Ignorable="d"
        Title="Авторизация" Height="500" Width="800" WindowStartupLocation="CenterScreen">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="100"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Image Source="Resources/beauty_logo.png" VerticalAlignment="Top" HorizontalAlignment="Left"></Image>
        <Grid Grid.Row="0" Background="#FFE1E4FF" Panel.ZIndex="-1"></Grid>
        <Frame  NavigationUIVisibility="Hidden" Grid.Row="1" Name="MainFrame" ContentRendered="MainFrame_ContentRendered" Background="#FFFF4A6D"></Frame>
        <TextBlock x:Name="Header" VerticalAlignment="Center" HorizontalAlignment="Center" Text="Бровушка" FontSize="38" FontFamily="Tahoma"/>
        <Button Content="Назад" Grid.Row="0" HorizontalAlignment="Right" x:Name="btnBack" Click="btnBack_Click"></Button>
    </Grid>
</Window>