ress is functional when the trade dress "is essential to the uses or purposes of the article or if it affects the cost or quality of the article." Inwmxl Labs., Inc- Ives Lobs., Inc.. 456 U.S. 844, 850 n. 10, 102 S.Ct. 2182, 2187 n. 10, 72 L.Ed.2d 606 (1982). A product's trade dress must be viewed in it