Display your prowess in men's fashion by teaming a white and navy horizontal striped crew-neck t-shirt and olive chinos for a casual combo. A good pair of white leather low top sneakers pulls this outfit together. So if it's a blazing hot afternoon and you want to look seriously stylish without putting in too much work, this ensemble will do the job in no time flat. Casual outfits for 30-year-old gents aren't actually that hard, as you can see.