The Mansard roof style replaced McDonald's original red-and-white restaurant design in 1969.
The new design used a dark brown exterior and a roofline resembling a mansard roof. McDonald's adopted it as part of a major visual change from the earlier buildings, whose red-and-white appearance and tall yellow arches had become strongly associated with the chain.
The redesign reflected changing architectural fashion and helped give restaurants a more substantial, contemporary appearance. The Golden Arches remained important signage even as the building itself changed.
The term can cause confusion because a mansard roof is a specific roof form with two slopes on each side, not simply any roof with a steep upper profile. McDonald's later introduced additional restaurant designs, but the 1969 style became a notable stage in its branding history.