How did Pope Gregory VII check the power of the holy roman emperor?

Pope Gregory VII checked the power of the Holy Roman Emperor by asserting the principle of papal supremacy, particularly through the famous Investiture Controversy. He opposed the practice of lay investiture, where secular leaders appointed church officials, claiming that only the pope had the authority to appoint bishops. This conflict culminated in the excommunication of Emperor Henry IV, which weakened his authority and led to a significant power struggle between the papacy and the monarchy. Gregory's actions reinforced the idea that the pope held spiritual authority over secular rulers.