"We like that orange hat."
Translation:Nos gusta aquel sombrero naranja.
Same question here. Spanish seems inconsistent that way. A yellow sombrero would definitely be amarillo, and a falda amarilla.
One way of saying "orange" in Spanish is "anaranjado" -- this only refers to the color and agrees with any noun it modifies (un libro anaranjado, una falda anaranjada, etc). Another way is to more or less say "it is the color of an orange" -- to use "naranja," the name of the fruit. When the name of an object is used as a representative example of a color in this way, it is not made to change gender. It retains its original form. Other examples include: rosa (rose/pink), turquesa (turquoise), esmerelda (emerald), lila (lilac), crema (cream).
(An advantage of maintaining the original noun form is the avoidance of ambiguous or even bizarre-sounding statements. "Naranja" may mean the citrus fruit, but "naranjo" refers to an orange tree. "Crema" may refer to dairy or cosmetic creams, but "cremo" is a form of the verb "to cremate.")
Found an explanation on thoughtco: "In traditionally correct usage, naranja or rosa as an adjective of color should remain unchanged, even when modifying a plural noun. However, Spanish (like all living languages) is changing, and in some areas, especially in Latin America, a construction such as los coches rosas would be perfectly acceptable and even preferable. You are right in stating the rule: Invariable adjectives (usually a noun being used as an adjective) don't change form regardless of whether they're describing something that is singular or plural."