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#include <QApplication>
#include <QWebSettings>
#include <QWebView>

namespace  {
char CSS[] = "html { filter: invert(); }";
}

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QApplication a(argc, argv);

    const QString cssUrl = QLatin1String("data:text/css;charset=utf-8;base64,") + QByteArray(CSS).toBase64();
    QWebSettings::globalSettings()->setUserStyleSheetUrl(QUrl(cssUrl));

    QWebView w;
    w.setContent("<html>Test</html>");
    w.show();

    return a.exec();
}