Is my prayer valid, and must I perform ghusl before every prayer if menstrual blood only appears at the beginning of the day and then stops for the rest of the day? And am I considered pure during these days?

If a woman sees blood, she is in a state of menstruation (hayd) and must abstain from prayer and all other things that a menstruating woman abstains from. When the blood stops, she must promptly perform ghusl (ritual bath) and pray. If the period of purity between two instances of bleeding is valid, she must make up the prayers she missed during her periods of purity. If the total duration of menstruation is one day and one night or more, it is considered hayd. If it is less, it is considered istihadah (irregular bleeding), except according to the Maliki school and Ibn Taymiyyah, who consider all blood seen by a woman to be hayd.