Set grid size to windows size - wpf

Question

I have the following code to fit the grid exactly to the window.
As you can see in the screenshot, the grid is running out of the window on the bottom and right side. Do you guys have any idea why this is happening? and how to do it properly?
<Window x:Class="WpfApp1.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"
mc:Ignorable="d"
Topmost="true"
Background="Aqua"
WindowStartupLocation="CenterScreen"
DataContext="{Binding Main, Source={StaticResource Locator}}"
Title="MainWindow" Height="500" Width="500">
<Grid
Width="{Binding ActualWidth, RelativeSource = {RelativeSource AncestorType = {x:Type Window}}}"
Height="{Binding ActualHeight, RelativeSource ={RelativeSource AncestorType = {x:Type Window}}}">
<Border Opacity=".9" BorderBrush="Blue" BorderThickness="2"/>
</Grid>
</Window>

Answer 1

If you bind the actual widths and heights of the window, the Grid will exceed the Window, as the content area is smaller than the window itself. Remove the bindings. The Grid will be sized automatically to occupy the available space if you do not explicitly set a Width and Height.
<Window x:Class="WpfApp1.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"
mc:Ignorable="d"
Topmost="true"
Background="Aqua"
WindowStartupLocation="CenterScreen"
DataContext="{Binding Main, Source={StaticResource Locator}}"
Title="MainWindow" Height="500" Width="500">
<Grid>
<Border Opacity=".9" BorderBrush="Blue" BorderThickness="2"/>
</Grid>
</Window>