NebulaLauncher/Nebula.Launcher/MessageBox/MessageWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        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:messageBox="clr-namespace:Nebula.Launcher.MessageBox"
        SystemDecorations="BorderOnly"
        mc:Ignorable="d" d:DesignWidth="600" d:DesignHeight="260"
        Width="600"
        Height="260"
        CanResize="False"
        x:Class="Nebula.Launcher.MessageBox.MessageWindow"
        Title="MessageWindow">
     <Grid ColumnDefinitions="*" RowDefinitions="30,*">
            <messageBox:MessageView
                Grid.Column="0"
                Grid.Row="0"
                Grid.RowSpan="2"
                x:Name="MessageView" />
            <Border
                
                BorderThickness="0,0,0,2"
                CornerRadius="0"
                Grid.Column="0"
                Grid.Row="0">
                <Border.BorderBrush>
                    <LinearGradientBrush EndPoint="100%,50%" StartPoint="0%,50%">
                        <GradientStop Color="#222222" Offset="0.0" />
                        <GradientStop Color="#442222" Offset="1.0" />
                    </LinearGradientBrush>
                </Border.BorderBrush>
                <Panel
                    Height="30"
                    PointerPressed="InputElement_OnPointerPressed">
                    <TextBlock
                        FontSize="10"
                        Foreground="White"
                        IsVisible="False"
                        Margin="15,0"
                        Text="Nebula Launcher"
                        VerticalAlignment="Center" />
                    <StackPanel
                        HorizontalAlignment="Right"
                        Margin="5,0,5,0"
                        Orientation="Horizontal"
                        Spacing="8">
                        <Button
                            Click="Close_Click"
                            Content="🗙"
                            Foreground="Azure" />
                    </StackPanel>
                </Panel>
            </Border>
        </Grid>
</Window>