Oh my I need these too.
I think you will be better off doing offline shopping for this one. If it's black leggings you're looking for then bring a piece of white something, stretch the leggings and see if the white comes through, if it does then whatever else can appear too. And for leggings that pass for pants you are either looking for something less tight fitting and loose or something that lacks the lines that tights have at the top.
... But by definition, leggings are: "(often called yoga pants) are tight or form-fitting, can be worn without anything over them, are a casual alternative to traditional pants, and are not see-through"
So any leggings should pass for pants and should not be see through.