The box’s position is calculated according to the normal flow (this is called the position in normal flow). Then the box is offset relative to its normal position. When a box B is relatively positioned, the position of the following box is calculated as though B were not offset.
The yellow box is shifted to the right, it overlaps the pink box but does not disturb the flow.
The offset does not create a "white" region (like
visibility:hidden does), it is just that there is nothing to show there.
Style the yellow box with
position:absolute (then search for it).
Style the yellow box with: