A system can include a housing that defines a first plane; a base that defines a second plane; and an adjustable hinge assembly that rotatably couples the base and the housing about an axis, where the hinge assembly includes permanent magnets that generate a first magnetic field and a second magnetic field orientable with respect to each other via rotation of the housing with respect to the base, where the first magnetic field and the second magnetic field include an aligned orientation, generate a clockwise restoring torque responsive to rotation of the housing in a first rotational direction from the aligned orientation, and generate a counterclockwise restoring torque responsive to rotation of the housing in a second, opposite rotational direction from the aligned orientation, and where the aligned orientation is adjustable to correspond to a selected angle between the first plane and the second plane.