UWP - TextBox background color

MainPage.xaml

<Page
    x:Class="UniversalAppTutorials.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:UniversalAppTutorials"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    >
    <StackPanel Padding="50" Background="AliceBlue">
        <!--
            Put TextBox inside a Border and set a background color
            for Border to display it as TextBox background color.
        -->
        <Border Background="Yellow">
        <TextBox
            x:Name="TextBox1"
            PlaceholderText="Input your name here."
            GotFocus="TextBox_GetFocus"
            />
        </Border>
    </StackPanel>
</Page>
MainPage.xaml.cs

using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;
using Windows.UI;
using Windows.UI.Xaml;


namespace UniversalAppTutorials
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        private void TextBox_GetFocus(object sender, RoutedEventArgs e) {
            // Set the TexBox focus background color
            TextBox1.Background = new SolidColorBrush(Colors.Yellow);
        }
    }
}