Create an minimalistic animation that represents an experience of diaphragmatic breathing. Visualize a minimalistic white line circle that gently expands for 3 seconds as the person inhales, remains stable for 3 seconds, and then gradually shrinks for 3 seconds as the person exhales. After exhaling, the circle remains stable for another 3 seconds before starting the cycle again. The movement of the circle should be smooth and rhythmic, similar to the natural process of breathing. The goal is to convey a sense of calm and relaxation during the practice of diaphragmatic breathing.