What does a sister on the rooftop mean?

"Tiantai Yijie" is the name given to a woman from Tiantai County, Taizhou City, Zhejiang Province. She has attracted attention for sharing her daily life and outfits on the Internet. Her dressing style is fashionable and simple, which is deeply loved and imitated by some netizens. Therefore, she is called "a sister from the rooftop" by netizens.