CS – no hilchos tznius in the “classic seforim”? See the sources brought in mishnah berurah 75 s”k2, and all of the sources brought in halichos bas yisroel. It’s literally all over the place.
It’s dealt with mainly regarding ervah l’inyan krias shma and talmud Torah. That’s where the poskim discuss which parts of the body must be covered and give the details you were taught. Elbows, knees, collarbone, etc..
That’s why thw sefer halichos bas yisroel was very important, because he compiled the poskim who discussed the details of tznius, but they were everywhere and needed little chidushim.
Regarding lashon hora, i am referring to details. What is the definition? What are the tenoim for toeles? When can one believe LH and when can you only be concerned about it? These aee things not discussed at all in the rishonim, st least not directly. The chofetz chaim labored greatly to learn this sugya and come to conclusions in halacha.
In tznius, there was no such need for the author of halichos bas yisroel to do that. Read the sefer, even though it was not written by a Lubavitcher..it won’t hurt your worldviiew.