Green div is inside of pink-div.
                Green div looks like green wedge on screen.
                Green div-plane is perpendicular to pink div-plane.
                This achived by rotation green div over own bottom edge by 90 deg;
                Pink div rotated over own right edge by 90 deg.
                Vanishing point for green div is x=150px is pointed by the green wedge.
                Vanishing point for pink div is x=0px and is pointed by incomplete pink wedge.

                These vanishing points are clearly different on screen.