What is the ruling on wearing a sleeveless hoop wedding dress, with a transparent veil covering it, and is a woman sinful if the dress is tight-fitting on the body?

A woman's 'awrah in front of other women is from the navel to the knee. In front of her mahrams, her entire body is 'awrah except for the extremities (head, forearms, and feet). As for non-mahram men, her entire body is 'awrah.

It is permissible for a woman to wear sleeveless clothing in front of other women, but it is not permissible in front of men (even if they are mahrams).

It is not permissible to wear tight clothing that defines the 'awrah and accentuates features, because a condition for modest clothing is that it must be loose.