A backrest includes a frame having a pair of laterally spaced upright members connected with longitudinally spaced upper and lower members. A flexible shell has opposite sides coupled to the upright members and upper and lower portions coupled to the upper and lower members. The shell includes first and second slots extending longitudinally along opposite sides of the shell inboard of locations where the shell is connected to the upright members, and one or more third slots extending laterally along the lower portion of the shell above a location where the shell is connected to the lower member. Terminal ends of the one or more third slots are spaced apart from lower terminal ends of the first and second slots. In other embodiments, the shell is a three-dimensional molded component having a plurality of openings. In various embodiments, the slots and/or openings provide different levels of compliance to the backrest.