ZoomedScene： objects scale problem

I have an issue when learn SlopeOfCircleExample of eoc.chapter6. The problem is that some objects of the zoomed-display area are rescaled when frame changes, but some objects remain the same scale. I know that 1b3b wants to keep some mobjects will remain the same width when frame changes, my question is how to set the width of these mobjects? The issue is attached below. I want the width of the lines in the zoomed frame is the same as in the other parts of the screen. And another minor issue is that the two lines should be tangent, however, in the zoomed area, they depart, does anyone know how to set it? Any help will be highly appreciated.