to what did corrie compare the green paint that would replace the gray of the former barracks

Someone suggests a former concentration camp, called Darmstadt. One a tour of the grounds, Corrie sees barbed wire and depressing concrete. However, Betsie’s vision for such a place reappears in Corrie’s memory and she tells her helps to add window boxes and to paint the dormitories green like the color of spring plants. In this way, Corrie completes the visions of which her sister Betsie dreamt.