Short shorts are never appropriate for the office. That's just my humble opinion, but my opinion is always right. And rarely humble. I have blogged previously about how casual my office is, but I do believe there is a limit, and shorts that can barely be seen under the long peasant top with which you have paired them go beyond that limit. (Ditto the slept-in-for-three-days-and-then-thrown-under-an-M15-bus t-shirt look. I get it, guy on the 3rd floor. You're creative, you need to wear jeans and a super-trendy t-shirt so people know it. But frankly, you look like a complete slob.)
So to all the chicks with whom I work who cannot bear to imprison their knees inside a fabric cell, I offer these. The cropped pant. A close cousin to the short short, but long enough to demonstrate that you know the difference between your office and Central Park. These flare out enough to ensure that no one will think you're wearing your little sister's pants. And they're available in more sizes at the store, on the off-chance that you don't wear a size 0.
Think about it. Do you really want to expose your naked thighs to the petri dish that is a New York City subway seat? There's no cure for some of what's on there.