What are the unique features of calligraphy in Yuan Dynasty?

In addition to the mainstream Zhao school, there are two noteworthy phenomena in calligraphy in Yuan Dynasty. First of all, the long-neglected seal script and official script began to reappear in the book world, and a number of famous seal script and official script writers emerged. Second, at the end of the Yuan Dynasty, hermit calligraphers, represented by Yang Weizhen and Ni Zan, began to consciously avoid or get rid of the influence of Zhao Meng's steady and elegant calligraphy style, and turned to the side, vertical, Gu Zhuo and even weird aspects.