Hyperlink colors does not work in QTextBrowser Qt5

#include <QtWidgets/QApplication>
#include <QtWidgets/QTextBrowser>

int main(int argc, char *argv[])
{
    QApplication a( argc, argv );
    QPalette p = a.palette();
    p.setBrush( QPalette::Link, Qt::red);
    a.setPalette( p );

    QTextBrowser browser;
    browser.setOpenExternalLinks(true);
    browser.setHtml("<a href='mailto:test@test.org'>test@test.org</a>");
    browser.show();

    return a.exec();
}