PR13/Kachaev_PR13/MainWindow.xaml

<Window x:Class="Kachaev_PR13.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:Kachaev_PR13"
        mc:Ignorable="d"
        Title="MainWindow" Height="426" Width="711.925">
    <Grid Height="447" VerticalAlignment="Top">
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="235"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="285"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <Button Content="Назад" HorizontalAlignment="Left" Margin="74,10,0,0" VerticalAlignment="Top" Width="75" Click="ButtonBack_OnClick"/>
        <Rectangle Fill="#FFF4F4F5" Grid.Row="2" Stroke="Black" RenderTransformOrigin="0.51,0.52" Grid.ColumnSpan="3" StrokeThickness="0" Margin="0,10,10,55"/>
        <Frame Content="MainFrame" Height="235" VerticalAlignment="Top" HorizontalAlignment="Left" Width="648" Source="Pages/AuthPage.xaml" Margin="10,0,0,0" Grid.Row="1" Grid.ColumnSpan="3" Navigated="MainFrame_OnNavigated"/>

    </Grid>
</Window>