Board heap problem-Can a board be piled up infinitely far and never dumped?

Poj1003Describes the problem of a heap board. The conclusion is that as long as there are an infinite number of boards, they can pile up in an infinitely distant place. This problem is also raised by the big scientific computing station.Mathematical Proof.

However, when I tried to verify the entire logic, why didn't I find out why I wouldn't heap the boards in this way? According to the conclusion, the layout of the three boards is shown in.

Consider the placement of three boards. If there are only two boards below, there is no problem. However, after the top part is put up, the above two parts are regarded as a whole, and the overall center of gravity is shown in the red dot. It has exceeded the right edge of the bottom board. How can this problem be solved?