Does the 72 hour limit include a layover within China?

We want to visit Beijing from December 30th to January 2nd. However, if we leave on January 2nd, our flight has a long layover in another city in China before moving on the Taiwan. Is this okay if we are not even leaving the airport, or will it violate the 72 hour rule since technically the flight leaving China is on Jan 3rd, even though the flight leaving is on the 2nd?