If you're a fan of casual outfits, why not wear a red puffer jacket with black sweatpants? When in doubt as to the footwear, go with a pair of white and red canvas low top sneakers. As you can see, it's extremely easy to look seriously stylish and stay toasty when colder weather hits, thanks to this outfit. Ideal if you're on a mission for some seriously inspiring 20-something casual style.