zIndex

const zIndex: {
  select: {
     list: {
        value: "{zIndex.popup}";
     };
  };
  modal: {
     overlay: {
        value: "{zIndex.scrim}";
     };
     dialog: {
        value: "{zIndex.floating}";
     };
  };
  base: {
     value: 0;
     unit: "none";
  };
  raised: {
     value: 1;
     unit: "none";
  };
  popup: {
     value: 200;
     unit: "none";
  };
  scrim: {
     value: 400;
     unit: "none";
  };
  floating: {
     value: 500;
     unit: "none";
  };
};