Gezuntheit why are/were opaque tights assur?
they are not asur it just a matter of what type is accepted in different communities. i know that from experience from when i was in manchester sem it was considered modern to wear black and back at home in us its frum. i asked my cousin in israel where this idea came from so she said its because when one wears black opaque for intance it shows very clearly where the feet are, two black sticks that strike out while sheer are not at stark the definitions where the lines are. i myself wear both types but this is just why some dont like the opaque look. if one is in a place where it is not the norm to wear dark
opaque then its better not to wear it but if one is in a place where its accepted then it is fine it is not a tznius issue then