Resizing rectangle

If you check on this website http://www.braingiants.com/v5/welcome.html you will see a rectangle that scales by clicking a button.
They also have a border around this rectangle that scales when i try this de border thickness also scales and i want the border thickness to be the same.
I came up with the idea the make 2 rectangles one that is bigger than the one on top this way i will have a border. Is this the easiest way or can someone tell me a better way.

Thanks in advance