For a cool and casual look, team a crew-neck t-shirt with a navy parka — these pieces work nicely together. A pair of white and black athletic shoes can instantly dial down a classic outfit. You might be thinking that just because you need to get bundled up you have to sacrifice smart style, but that's just not true, and this outfit is proof. This pairing should erase any doubts you had about wearing casual clothes as a gentleman in his thirties.