<Grid

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"

Height="450" Width="800">

<Viewbox HorizontalAlignment="Right" VerticalAlignment="Bottom">

<Grid x:Name="RootGrid" Width="800" Height="450" Background="WhiteSmoke">

<StackPanel>

<StackPanel.Resources>

<ControlTemplate x:Key="btnTemplate" TargetType="Button">

<Grid x:Name="RootGrid" Background="Cyan">

<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>

</Grid>

</ControlTemplate>

<Style TargetType="Button">

<Setter Property="Template" Value="{StaticResource btnTemplate}"/>

</Style>

</StackPanel.Resources>

<Button Width="200" Height="100" Content="Button A"/>

<Button Width="200" Height="100" Content="Button B" Margin="0,10"/>

</StackPanel>

</Grid>

</Viewbox>

</Grid>