However regional variations remained important, even when, by the late 14th century, a coherent universal style known as International Gothic had evolved, which continued until the late 15th century, and beyond in many areas. The principal media of Gothic art were sculpture, panel painting, stained glass, fresco and the illuminated manuscript, though religious imagery was also expressed in metalwork, tapestries and embroidered vestments. The architectural innovations of the pointed arch and the flying buttress, allowed taller, lighter churches with large areas of glazed window.