The grim subtext of German fairy tales had it right: When you ask the mirror on the wall to judge the fairest of them all, the answer can open up the darkness within — dipping self-esteem, crippling anxiety or envy. And unlike fairytales, there may not be happily-ever-afters at the end of the ordeal, especially if the mirror happens to be social-media platforms where the metric of beauty is set by algorithms primed to fuel insecurities.........