Why does the narrator's mother buy her a miniskirt?

The narrator's mother buys her a miniskirt as a way to support her daughter's burgeoning sense of independence and self-expression. This gesture reflects a shift in their relationship, showcasing the mother's understanding of her daughter's desire to fit in with her peers and embrace a more modern style. It signifies a moment of connection and acceptance between them, highlighting the complexities of growing up and navigating societal expectations.