Z-index Values

$z-layers: (
  "max":              9999, 
  "fullscreen":       1700,
  "modal": (
    "tooltip":        1600,   
    "popover":        1500,
    "dropdown":       1400,
    "content":        1300,
    "overlay":        1200,
  ),
  "mobile-composer":  1100,
  "header":           1000,
  "tooltip":          600,
  "composer": (
      "popover":      500,
      "content":      400,
  ),
  "dropdown":         300,  
  "usercard":         200,
  "timeline":         100,
  "base":             1
  );
// Declare:
z-index: z("base") + num;