Center a vertically oriented grid in wpf - wpf

Question

I started doing the UI for an app in WinForm but I just read about WPF and I decided to re-do my work on it. But since is a new think I ran in a small problem:
As you can see in the screenshot bellow I have 3 vertical buttons that are centered on the main form. How can I achieve the same thing in WPF? I've tried any value I could find to change position but all of them failed.
Here is my main form XAML:
<Window x:Class="YouTubeMusicPlayerWpf.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:YouTubeMusicPlayerWpf"
xmlns:fa="http://schemas.fontawesome.io/icons/"
mc:Ignorable="d" Height="500" Width="900" Background="Black" WindowStyle="None" AllowsTransparency="true" WindowStartupLocation="CenterScreen" Name="mainWindow">
<WindowChrome.WindowChrome>
<WindowChrome ResizeBorderThickness="6" CornerRadius="0" GlassFrameThickness="0">
</WindowChrome>
</WindowChrome.WindowChrome>
<StackPanel Background="#FF201E2B">
<!-- TitleBar buttons -->
<Grid HorizontalAlignment="Right">
<StackPanel Orientation="Horizontal">
<Button fa:Awesome.Content="WindowMinimize" Background="Transparent" Foreground="White" VerticalAlignment="Stretch" Padding="8" BorderThickness="0" WindowChrome.IsHitTestVisibleInChrome="True" Name="minButton" Click="MinButton_OnClick"></Button>
<Button fa:Awesome.Content="WindowMaximize" Background="Transparent" Foreground="White" VerticalAlignment="Stretch" Padding="8" BorderThickness="0" WindowChrome.IsHitTestVisibleInChrome="True" Name="maxButton" Click="MaxButton_OnClick"></Button>
<Button fa:Awesome.Content="WindowClose" Background="Transparent" Foreground="White" VerticalAlignment="Stretch" Padding="8" BorderThickness="0" WindowChrome.IsHitTestVisibleInChrome="True" Name="closeButton" Click="CloseButton_OnClick"></Button>
</StackPanel>
</Grid>
<!-- Menu Buttons-->
<Grid HorizontalAlignment="Left" VerticalAlignment="Center">
<StackPanel Orientation="Vertical">
<Button fa:Awesome.Content="Youtube" FontSize="40" Background="#00000000" Foreground="White" BorderBrush="Transparent" Width="80" Height="80" VerticalAlignment="Center" HorizontalAlignment="Center"></Button>
<Button fa:Awesome.Content="Music" FontSize="40" Background="#00000000" Foreground="White" BorderBrush="Transparent" Width="80" Height="80" VerticalAlignment="Center" HorizontalAlignment="Center"></Button>
<Button fa:Awesome.Content="Download" FontSize="40" Background="#00000000" Foreground="White" BorderBrush="Transparent" Width="80" Height="80" VerticalAlignment="Center" HorizontalAlignment="Center"></Button>
</StackPanel>
</Grid>
</StackPanel>
</Window>

Answer 1

The problem is your root element. Replace the StackPanel by a grid and problem solved.
Bonus : if you are new to WPF, I show you how to refactorize your styles.
<Grid Background="Black">
<Grid.Resources>
<!-- Exemple of a style with a key to reuse -->
<Style x:Key="LeftButtonStyle" TargetType="Button">
<Setter Property="FontSize" Value="40" />
<Setter Property="Width" Value="80" />
<Setter Property="Height" Value="80" />
<Setter Property="Background" Value="#00000000" />
<Setter Property="Foreground" Value="White" />
<Setter Property="BorderBrush" Value="Transparent" />
</Style>
</Grid.Resources>
<!-- TitleBar buttons -->
<StackPanel
HorizontalAlignment="Right"
VerticalAlignment="Top"
Orientation="Horizontal">
<StackPanel.Resources>
<!-- Exemple of a implicit styles that will be set to each child with a matching type -->
<!-- Notice there is no x:Key -->
<Style TargetType="Button">
<Setter Property="Background" Value="Transparent" />
<Setter Property="Foreground" Value="White" />
<Setter Property="Padding" Value="8" />
<Setter Property="BorderThickness" Value="0" />
</Style>
</StackPanel.Resources>
<Button Content="b1" />
<Button Content="b2" />
<Button Content="b3" />
</StackPanel>
<!-- Menu Buttons -->
<StackPanel
HorizontalAlignment="Left"
VerticalAlignment="Center"
Orientation="Vertical">
<Button Content="icon" Style="{StaticResource LeftButtonStyle}" />
<Button Content="icon" Style="{StaticResource LeftButtonStyle}" />
<Button Content="icon" Style="{StaticResource LeftButtonStyle}" />
</StackPanel>
</Grid>
Notice there is neither RowDefinitions nor ColumnDefinitions.
Here is how to do the same thing with place to set the content (a red box for exemple).
<Grid Background="Black">
<Grid.Resources>
<!-- Exemple of a style with a key to reuse -->
<Style x:Key="LeftButtonStyle" TargetType="Button">
<Setter Property="FontSize" Value="40" />
<Setter Property="Width" Value="80" />
<Setter Property="Height" Value="80" />
<Setter Property="Background" Value="#00000000" />
<Setter Property="Foreground" Value="White" />
<Setter Property="BorderBrush" Value="Transparent" />
</Style>
</Grid.Resources>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition />
</Grid.RowDefinitions>
<!-- TitleBar buttons -->
<StackPanel
Grid.Column="1"
HorizontalAlignment="Right"
Orientation="Horizontal">
<StackPanel.Resources>
<!-- Exemple of a implicit styles that will be set to each child with a matching type -->
<!-- Notice there is no x:Key -->
<Style TargetType="Button">
<Setter Property="Background" Value="Transparent" />
<Setter Property="Foreground" Value="White" />
<Setter Property="Padding" Value="8" />
<Setter Property="BorderThickness" Value="0" />
</Style>
</StackPanel.Resources>
<Button Content="b1" />
<Button Content="b2" />
<Button Content="b3" />
</StackPanel>
<!-- Menu Buttons -->
<StackPanel
Grid.RowSpan="2"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Orientation="Vertical">
<Button Content="icon" Style="{StaticResource LeftButtonStyle}" />
<Button Content="icon" Style="{StaticResource LeftButtonStyle}" />
<Button Content="icon" Style="{StaticResource LeftButtonStyle}" />
</StackPanel>
<Grid Background="Red" Grid.Row="1" Grid.Column="1"/>
</Grid>