function detectDevice() {
  if ((/ipad|android 3.0|xoom|sch-i800|playbook|tablet|kindle/i.test(navigator.userAgent.toLowerCase()))) {
    return 'tablet';
  }
  if ((/iphone|ipod|android|blackberry|opera|mini|windows\sce|palm|smartphone|iemobile/i.test(navigator.userAgent.toLowerCase()))) {