Amanda Bynes just added a metallic twist to her ever-evolving style. The former actress, 40, debuted a pair of bright blue brows in a Monday, May 4, video shared via her Instagram Stories, one day before she was spotted on a rare public outing with boyfriend Zachary Khan. Bynes showed off her cobalt-lined arches while doing her makeup in the car. “Cigarette stains >,” she captioned the video. Amanda Bynes Explains Why She Can't Wear Tooth Gems T…