illumination of manuscript pages, cosmopolitan style, elegant, mannered and sophisticated. realistic details and naïve naturalistic were shown in their paintings. this era is____

This description points to the International Gothic era. In illuminated manuscripts, the International Gothic style (late 14th–early 15th century) is known for a cosmopolitan courtly refinement, elegant and mannered figures, sophisticated page designs, and a blend of realistic detail with still somewhat naïve naturalism in faces, landscapes, and settings.