How to use the @uifabric/fluent-theme.NeutralColors.gray130 function in @uifabric/fluent-theme

import { NeutralColors, SharedColors } from '@uifabric/fluent-theme';
import { DefaultFontStyles, FontWeights } from 'office-ui-fabric-react';
import { ISetupWizardActionBarStyles } from './SetupWizardActionBar.types';

const actionLinkStyle = {
  color: NeutralColors.gray130
};
export const getStyles = (): ISetupWizardActionBarStyles => {
  return {
    root: {
      whiteSpace: 'nowrap',
      width: '100%',
      display: 'flex',
      flexDirection: 'row',
      border: `1px solid ${NeutralColors.gray40}`,
      height: '75px',
      alignItems: 'center'
    },
    backAction: [
      DefaultFontStyles.medium,
      actionLinkStyle,
      {

export const getSetupWizardStyles = (): ISetupWizardStyles => {
  return {
    wizardContainer: [
      DefaultFontStyles.medium,
      {
        color: NeutralColors.gray130,
        display: 'flex',
        flexDirection: 'column',
        height: '100%'
      }
    ],
    titleSection: {
      border: `1px solid ${NeutralColors.gray40}`,
      height: '75px'
    },
    actionBarSection: {
      whiteSpace: 'nowrap',
      width: '100%',
      display: 'flex',
      flexDirection: 'row',
      border: `1px solid ${NeutralColors.gray40}`,
      height: '75px',

&:not(:last-child) {
    border-bottom: 1px solid ${NeutralColors.gray30};
  }
`;

export const customObjectFieldItem = css`
  flex: 1;

  & + & {
    margin-left: 20px;
  }
`;

export const customObjectFieldLabel = css`
  color: ${NeutralColors.gray130};
  font-size: 12px;
  margin-left: 7px;
  padding-bottom: 5px;
`;