Is the prayer of one who prays in a light garment and very short trousers valid, and what should they be advised to do?

For a male worshipper, it is obligatory to cover the area between the navel and the knee with an opaque garment. If the garment is thin and reveals the skin color, the prayer is not valid with it. As for a female, she must cover her entire body with an opaque, thick garment during prayer. It is permissible for her to uncover her face and hands (with the preference being to cover the hands), and it is not permissible for her to pray in thin clothes that reveal her body.