Abstract: A seating device such as a chair or sofa. The seating device includes a frame, a seat platform supported by the frame, and a backrest attached to the seat platform. The seat platform has opposite front and rear ends. The backrest has a first backrest portion extending upwardly from proximate the rear end of the seat platform. A lower end of the first backrest portion is positioned adjacent to an upper surface of the seat platform. The first backrest portion is capable of being moved forwardly and rearwardly along the upper surface of the seat platform while the lower end remains proximate the upper surface of the seat platform. A backrest-adjustment powered actuator operates the backrest for moving at least the first backrest portion forwardly and rearwardly partially along the upper surface of the seat platform to adjust an effective depth of the seat platform.