A dark green harrington jacket and navy jeans are must-have menswear essentials if you're figuring out a casual closet that holds to the highest style standards. Why not take a classier approach with shoes and introduce dark brown leather derby shoes to the mix? Keep this ensemble in your front hall wardrobe when warmer days are here, and rest assured, you'll save a ton of time getting dressed on more than one occasion. So if you're on a mission for a stylish yet mature outfit, this just might be it.