The shorts are prolly meant to go with the top on the desk. There are some two-piece suits for females that have shorts instead of the normal panties look or skirt. Meant to give them more of a "tomboyish" feel without reverting to the fashion faux pas that is the full body covering racing suit.
Man this gives me Tatsuki Fujimoto vibe (Sayonara Eri and Look Back ), character's thoughts, emotion not expressed through words but through drawings and actions,... I wish more mangaka would do this.