#include <QApplication>
#include <QMainWindow>
#include <QPushButton>
#include <QLabel>
#include <QVBoxLayout>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QMainWindow mainWindow;
    mainWindow.setWindowTitle("Hello World Qt");
    mainWindow.resize(400, 300);

    // Create central widget and layout
    QWidget *centralWidget = new QWidget(&mainWindow);
    QVBoxLayout *layout = new QVBoxLayout(centralWidget);

    // Create hello world label
    QLabel *helloLabel = new QLabel("Hello World!", centralWidget);
    helloLabel->setAlignment(Qt::AlignCenter);
    helloLabel->setStyleSheet("font-size: 24px; font-weight: bold;");

    // Create close button
    QPushButton *closeButton = new QPushButton("Close", centralWidget);
    closeButton->setStyleSheet("font-size: 16px; padding: 10px;");

    // Connect button to close action
    QObject::connect(closeButton, &QPushButton::clicked, &mainWindow, &QMainWindow::close);

    // Add widgets to layout
    layout->addStretch();
    layout->addWidget(helloLabel);
    layout->addWidget(closeButton);
    layout->addStretch();

    // Set central widget
    mainWindow.setCentralWidget(centralWidget);

    // Show the window
    mainWindow.show();

    return app.exec();
}