savelev_avt/Pages/CustomerMenu.xaml

<Page x:Class="savelev_avtor.Pages.CustomerMenu"
      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" 
      xmlns:local="clr-namespace:savelev_avtor.Pages"
      mc:Ignorable="d" 
      d:DesignHeight="450" d:DesignWidth="800"
      Title="CustomerMenu">

    <Grid Background="White">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="289*"/>
            <ColumnDefinition Width="203*"/>
            <ColumnDefinition Width="308*"/>
        </Grid.ColumnDefinitions>
        <Button Content="Переход1" HorizontalAlignment="Left" Margin="0,141,0,0" VerticalAlignment="Top" Width="203" Grid.Column="1" Height="20" Click="ButtonPage1_OnClick"/>
        <Button Content="Переход2" HorizontalAlignment="Left" Margin="0,166,0,0" VerticalAlignment="Top" Width="203" Grid.Column="1" Height="20" Click="ButtonPage2_OnClick"/>
        <Button Content="Переход3" HorizontalAlignment="Left" Margin="0,191,0,0" VerticalAlignment="Top" Width="203" Grid.Column="1" Height="20" Click="ButtonPage3_OnClick"/>

    </Grid>
</Page>