WPF Textbox visible in Designer but not application

I’m brand new WPF so I may be missing something obvious. I’ve got a TextBox in the designer, that looks fine and is visible, however, when running the app it isn’t visible while the other elements are still visible.

Designer:

Application:

Xaml:

<Window x:Class="Windows.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:Windows"
        mc:Ignorable="d"
        Title="UniPaste for Windows" Height="450" Width="800"
        Background="#333">
    <Grid>
        <TextBlock TextWrapping="Wrap" Text="UniPaste for Windows" Margin="0,0,0,348" TextAlignment="Center" VerticalAlignment="Center" Foreground="White" FontSize="32" FontFamily="Consolas Bold"/>
        <TextBlock TextWrapping="Wrap" Text="Email" Margin="0,90,0,0" TextAlignment="Center" VerticalAlignment="Top" Foreground="White" FontSize="24" FontFamily="Consolas"/>
        <TextBox Name="Email" Margin="340,123,340,290" Background="White" Height="23" TextChanged="EmailChanged"/>
    </Grid>
</Window>

>Solution :

Take advantage of the Grid component and its row and column definitions to align the elements you want.
What was happening is that at runtime the textbox had no line to attach to

<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"
    xmlns:local="clr-namespace:WpfApp1"
    mc:Ignorable="d"
    Title="MainWindow" Height="450" Width="800"
    Background="#333">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
    </Grid.RowDefinitions>
    <TextBlock Grid.Row="0" 
               Margin="0 25 0 0"
               TextWrapping="Wrap" 
               Text="UniPaste for Windows" 
               TextAlignment="Center" 
               VerticalAlignment="Center" 
               Foreground="White" 
               FontSize="32" 
               FontFamily="Consolas Bold"
               />
    <TextBlock Grid.Row="1" 
               Margin="0 25 0 0"
               TextWrapping="Wrap" 
               Text="Email" 
               TextAlignment="Center" 
               VerticalAlignment="Top" 
               Foreground="White" 
               FontSize="24" 
               FontFamily="Consolas"/>
    <TextBox Grid.Row="2"   
             Name="Email" 
             Margin="0 25 0 0"
             HorizontalAlignment="Center" 
             Background="White" 
             Height="23" Width="100" 
             TextChanged="EmailChanged" 
             />

</Grid>

Runtime Window