An absolutely positioned element within a relatively positioned div should not be affected by the css declaration text-align:center. Such absolutely positioned element should be positioned within its offetParent and should ignore the text-align:center property which apply anyway to inline elements, not to block-level elements.
The red box should be positioned at top: 12px; and left: 36px; from the green bordered div, not within the <img>
This is where should be positioned the red box (screen shot: 624
pixels wide):