/***
 * Pixels to Ems function
 *
 * Converts pixels to EMs so we can keep our units consistent.  Assumes 1em is 16px, or you can pass a different base.
 *
 * scss:
 *   pxToEm($px[,$base]);
 *
 * @param $px - unitless integer to convert to rems
 * @param $base - pixels to count as one em. Defaults to 16
 */
@function pxToEm ($px, $base: 16) {
  @return 1em * stripUnits($px) / $base;
}