Is it possible to take a rectangular image, turn it into a square, then circle?

I managed to turn my square picture into a circular image with border-radius. But all my rectangles turn into an elliptical shape. I also want the images to be responsive and to shrink smaller for mobile devices. I managed to make them square then circular by specifying the width and height in pixels. Then doing border-radius. But its not responsive it just stays the same size no matter the screen size :cold_sweat: