"要不干脆用carpet stairs 得了,还省钱。不过好像以后想换成木楼梯很麻烦+费钱, 而且只能换踏板而已。" You are right. However, it does not look pretty and carpet can get dirty easily. What you can do is that you leave the stairs with carpet firstly. If you do not like it in the future, you can change it.