Design view being different from actual view when running

<Page x:Class="TEUD_GUI_Version.MainPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:local="clr-namespace:TEUD_GUI_Version"
      mc:Ignorable="d" 
      d:DesignHeight="450" d:DesignWidth="450"
      Title="MainPage">

    <StackPanel Background="White" MaxHeight="450" MaxWidth="450">
        <Label
            FontWeight="Bold"
            FontSize="20"
            HorizontalContentAlignment="Center"
        >The Escapists Ultimate Decompiler</Label>
        <Button
            x:Name="ProjButton"
            Margin="0,10,0,0"
            Width="400"
        >To .proj</Button>

        <Button
            x:Name="CmapButton"
            Margin="0,10,0,0"
            Width="400"
        >To .cmap</Button>

        <Button
            x:Name="MapButton"
            Margin="0,10,0,0"
            Width="400"
        >To .map</Button>

        <Button
            x:Name="DecryptButton"
            Margin="0,100,0,0"
            Width="400"
        >Decrypt Any File</Button>

        <Button
            x:Name="EncryptButton"
            Margin="0,10,0,0"
            Width="400"
        >Encrypt Any File</Button>

        <Button
            x:Name="AboutButton"
            Margin="0,125,0,0"
            Width="400"
        >About</Button>
    </StackPanel>
</Page>