Faux pas?

No. You can mix any and all neutrals at will. If you are worried about it, add one other black, and one other brown, element to the outfit.

Or something that has both, like a string of beads that contains both black ones and brown ones, a peep of cami with a black and brown print, etc.
 
I'm the wrong person to ask :shrugs: I have no style whatsoever. I wear what I'm comfortable in and hang what other people think, and yes I wear black ankle boots under my jeans and carry a dark brown handbag :yahoo:
 
I heard for guys that it's a faux pas to wear a brown belt with black shoes and vice versa. I was surprised to hear that from so many sources (like tv, magazines, and even people). I personally think it's fine and depends on the entire outfit, and am very glad to know I'm not the only one