EmployeeTracker/InvestTracker/MainWindow.xaml

<Window x:Class="InvestTracker.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:InvestTracker"
        xmlns:commands="clr-namespace:InvestTracker.Commands"
        mc:Ignorable="d"
        Title="ИнвестУчёт" Height="720" Width="1280">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="32px"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>

        <Grid Grid.Row="0">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="64px"/>
            </Grid.ColumnDefinitions>

            <Label Grid.Column="0" FontSize="18" HorizontalAlignment="Center">ИнвестУчёт</Label>
            <Button Grid.Column="1" Command="{x:Static commands:DataCommands.ExitCommand}">Выход</Button>
        </Grid>

        <!--Body-->
        <Grid Grid.Row="1">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="256px"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>

            <Grid Grid.Row="0" Grid.Column="0" Margin="10">
                <Grid.RowDefinitions>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                </Grid.RowDefinitions>

                <Button Style="{StaticResource NavButton}" Grid.Row="0" Command="{x:Static commands:NavigationCommands.NavigateFrame}">Сотрудники</Button>
                <Button Style="{StaticResource NavButton}" Grid.Row="1">Клиенты</Button>
                <Button Style="{StaticResource NavButton}" Grid.Row="2">Договора</Button>
                <Button Style="{StaticResource NavButton}" Grid.Row="3">Ценные бумаги</Button>
                <Button Style="{StaticResource NavButton}" Grid.Row="4">Сделки</Button>
                <Button Style="{StaticResource NavButton}" Grid.Row="5">Справка</Button>
            </Grid>
            <Frame Padding="5" x:Name="MainFrame" Source="Views/WelcomeView.xaml" Grid.Column="1" NavigationUIVisibility="Hidden"/>
        </Grid>

    </Grid>
</Window>