<Window
    Height="250"
    Title="WARNING"
    Width="500"
    WindowStartupLocation="CenterOwner"
    x:Class="Project.View.PopUp"
    xmlns="https://github.com/avaloniaui"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <StackPanel Margin="20" Spacing="10">
        <TextBlock HorizontalAlignment="Center" Text="One or more of your inputs are missing or wrong." />
        <TextBlock HorizontalAlignment="Center" Text="All fields must be filled." />
        <TextBlock HorizontalAlignment="Center" Text="Your username needs at least 4 characters." />
        <TextBlock HorizontalAlignment="Center" Text="Your password needs at least 8 characters." />
        <TextBlock HorizontalAlignment="Center" Text="Make sure your email is correct." />
        <Button
            Click="OkButton_Click"
            Content="OK"
            HorizontalAlignment="Center"
            Width="80" />
    </StackPanel>
</Window>