How casual can a casual dress code be?

Hi all, I will be working at an internship this summer where the office dress code is very casual. Having visited the office before, it truly is casual i.e. everyone was in a t-shirt and jeans, sneakers, and my boss had tattoos visible. However, is it acceptable for me to wear clothing items such as shorts (pretty short) or sleeveless tops/spaghetti strap tops? I don't know if those would be inappropriate considering they do show off more skin. At the same time, I am in SoCal so it is very hot during the summer and it would suck to wear long jeans all the time... I know the office has at least one more woman there, but I am not sure of her style of dress.