I have several dresses and skirts that aren't exactly see through, but if I'm out in the sun, you can clearly see the outline of my legs. You can't see what color my panties are or anything, just the outline of my legs. Is it ok to wear this in public or not?
If it can be considered appropriate in the office, then it is extremely safe anywhere else. And since it doesn't really show anything, I am sure you are worried for no reason. It is good that you ask yourself though, because some girls wear outfits that are seriously wrong or unflattering.