What is the ruling on the fast of a woman who became pure at noon during a Ramadan day, and only prayed Dhuhr, and did not pray the rest of the obligatory prayers except Fajr, and completed her fast? Is her fast valid, or must she make up that day?

If menstruation stops after Fajr, that day's fast is not valid, and it must be made up, even if she intended to fast and completed it, due to the presence of menstruation. However, if she becomes pure before Fajr and intends to fast, her fast is valid even if she does not perform ghusl until after Fajr. But delaying ghusl until Dhuhr, when it is possible to perform it earlier, is a grave sin because it causes the loss of the Fajr prayer.