This combination of a crew-neck sweater and a white short sleeve shirt is proof that a safe casual ensemble can still be extra dapper. Why not introduce a pair of charcoal athletic shoes to the mix for a more laid-back vibe? So as you can see, it's super easy to look awesome and stay comfy when colder weather comes, all thanks to ensembles like this one. Overall, a great example of casual fashion for 20-year-old gents.