Casual shorts are one of my favourites. They give you a smart look, and yet comfy and more fun.
You can choose the plain colour and play with the designs, a high waist retro look (top right), or a sweet Korean with lace lining. If you want to go a bit more bold, try those with colours and pattern and be funky with them!
P.S: Belts can do a wonderful job in touching up your whole look. They aren't expensive so get a few colours and play with them, you won't regret at all! <3