mt mehdi: It has also been repeated that tznius is for a woman what Torah learning is for a man. We can keep something only to the extent that we know it. If we educate ourselves in Torah, we’ll learn tznius throughout: from the way Chava was formed, to the Imahos (“Hinei Ba’ohel”, and many more), to Dina, to the women in Mitzrayim with the mirrors, to the Kohen Gadol using a ramp, to “K’doshim Tihyu”, “Hatzne’a Leches” and “V’haya Kadosh”.
These are just a few of the many lines of the Torah devoted to tznius.
Just as in other areas, the actual Halochos of tznius are Torah She’baal Peh.