Why not consider wearing a grey crew-neck t-shirt and black vertical striped chinos? Both of these items are super practical and look amazing when married together. Inject a mellow touch into your ensemble by rounding off with navy athletic shoes. Casual looks for 20-something gents aren't actually that hard, as you can see here.
To put together a relaxed menswear style with a modern finish, you can always rely on a grey crew-neck t-shirt and black vertical striped chinos. If you want to break out of the mold a little, grab a pair of black athletic shoes. This combo demonstrates that in your late 20s your sartorial options are pretty much limitless.
Marry a grey crew-neck t-shirt with black vertical striped chinos for a laid-back kind of polish. The whole ensemble comes together wonderfully when you complete this outfit with black leather low top sneakers. Guys who are curious how to pull off modern off-duty style as you move through your 20s, this combination should answer your question.