Pairing a white and black floral short sleeve shirt with jeans is an on-point option for a casually cool look. For something more on the cool and laid-back end to complete this look, complement your getup with a pair of grey high top sneakers. A killer getup like this one is just what you need when hot weather hits. Those wondering how to rock modern off-duty dressing as you mature into your 30s, you have your answer.