Her dress reflects the Spanish influence in Italy. Christine of Lorraine's Wikipedia article is here.
When you're a conservative, it helps to know what you're conserving. She had problems with this. According to this Web site, she played a key role in the trial of Galileo. She felt observations that clashed with the Bible had to be in error. The USA, at least, still hasn't resolved the issue that Galileo's trial should have resolved in 1613. The Vatican now runs an astronomical observatory while conservative US politicians deny scientific evidence about biological evolution and, alarmingly, climate change.