$z-index: (
  "auto": auto,
  "below": -1,
  "default": 1,
  "slideshow-slide": 3,
  "middle": 10,
  "top": 20,
  "global-header": 100,
  "map-holder-open": 200,
  "video-overlay-close": 1000,
  "popup": 4000,
  "dialog": 5000,
  "dropdown": 6000,
  "overlay": 7000,
  "menu": 8000,
  "modal": 9000,
  "toast": 10000
);