📄 src/App/Views/MainWindow.axaml.cs
using Avalonia.Controls;
using Avalonia.Input;

namespace MMirror.App.Views;

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    protected override void OnPointerEntered(PointerEventArgs e)
    {
        base.OnPointerEntered(e);

        Classes.Add("active");
    }

    protected override void OnPointerExited(PointerEventArgs e)
    {
        Classes.Remove("active");

        base.OnPointerExited(e);
    }
}