CourseProject_ended/Hotel_Course_Project/MainWindow.xaml

<Window x:Class="Hotel_Course_Project.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:materialDesign="https://materialdesigninxaml.net/winfx/xaml/themes"
        xmlns:local="clr-namespace:Hotel_Course_Project"
        mc:Ignorable="d"
        Title="{Binding ElementName=MainFrame,Path=Content.Title}" Height="450" Width="800" WindowStartupLocation="CenterScreen" ResizeMode="NoResize">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="40"></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>

        <Button HorizontalAlignment="Left" Name="BackBtn" Click="BackBtn_Click">Назад</Button>
        <Frame Name="MainFrame" Grid.Row="1" NavigationUIVisibility="Hidden" ContentRendered="MainFrame_ContentRendered"></Frame>
    </Grid>
</Window>