Is this too casual to wear to a wedding?

If it's an outdoor wedding on the beach or in a park, then you could wear the tie dye skirt and top with sandals but if it's in a church, I would wear the red top with a solid skirt you have and dressy flats or heels. Otherwise, you could just wear a solid color dress (any color other than white) with cute shoes. Have fun at the wedding!! : P