What is the ruling on opening a women's beauty salon staffed only by women, and will the owner be held accountable for the unveiling of non-hijabi women after they are beautified there? What is the ruling on performing حمامات (baths/spa treatments) that require a woman to uncover in front of another female worker?

It is not permissible for a salon to adorn immodestly dressed women, because it is assisting them in sin, in accordance with the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." Similarly, a hammam (bathhouse) is not permissible if it requires a woman to uncover herself before a female worker who might see or touch what is forbidden for one woman to see or touch of another, which is the area between the navel and the knee.