Cool. If your boss saw you looking at this and gave you a weird look, that's enough for NSFW. It doesn't mean "porn" it means "not safe for work" and also coveres gore, iconography (swastikas, hammer and sickle etc) and some other things.
Why, most bosses understand their employees aren't working 100% of the time because that's impossible to maintain. People take breaks to destress, to reset their mind etc. Expecting them not to is 100% the wrong thing.
Depending on where in the world you live, a very slight outline of a nipple is not considered erotic or “pornographic”. Wild that to some it’s in the same category as swastikas and hammer and sickles.