There are many words that are antonyms for "art serious about", such as lighthearted, whimsical, playful, and comedic. These words imply a sense of levity and humor rather than a focus on the seriousness of art. For instance, a lighthearted art exhibit may feature bright colors, simple shapes, and humorous subject matter. Meanwhile, a serious art exhibit may feature complex imagery, dark colors, and thought-provoking themes. It all depends on the artist's intent and style. Regardless, it's important to remember that art doesn't always have to be serious or heavy - sometimes, it's okay to just have fun with it.