A black cardigan will always work, but maybe not so much with this ensemble. I would wear a darker and more flattering pants (or a skirt) to allow the top to be the focal point. The top is meant to draw attention to your face, that's what needs to be the focal point, always. A lot of things going on on the bottom, or a lot of unrelated colors just take away from You.A dress would also work.If it is a drawstring cardigan, why not pull the string close. If not, consider using a narrow black belt (and still leaving it open).Hope this helps your decision making!