“Tznius in front of Non Jews”.
I think the title for this thread is wrong.
Does it matter if the person in front of you is a co-religionist or of the same gender? Shivisi hashem linegdi tamid.
I use the following rule of thumb. If I wont do it/dress that way in front of my boss, I sure as heck am not doing it in front of the ribbono shel olam.