Updated Gruntfile.js with Working Autoprefixer

Gruntfile.js

'use strict';

// Packages
const fiberLibrary = require('fibers');
const sassLibrary = require('node-sass');

module.exports = function(grunt) {

	// load all tasks
	require('load-grunt-tasks')(grunt, {scope: 'devDependencies'});

	grunt.initConfig({
		pkg: grunt.file.readJSON('package.json'),
		watch: {
			files: ['assets/scss/**/*.scss', 'assets/js/**/*.js'],
			tasks: ['sass', 'postcss', 'cssmin', 'concat', 'uglify'],
			options: {
				livereload: true,
			},
		},
		sass: {
			default: {
				options : {
					implementation: sassLibrary,
					fiber: fiberLibrary,
					style : 'expanded',
					sourceMap: true
				},
				files: {
					'css/style.css':'assets/scss/style.scss',
					'css/jobvite.css':'assets/scss/jobvite.scss'
				}
			}
		},
		postcss: {
			options: {
				map: true,
				processors: [
					require('autoprefixer')({browsers: 'last 2 versions, > 2%'}),
				]
			},
			dist: {
				files: [{
					src: ['css/*.css', 'css/!*.min.css'],
				}]
			}
		},
		cssmin: {
			options: {
				aggressiveMerging : false,
				sourceMap: true
			},
			target: {
				files: [{
					expand: true,
					cwd: 'css',
					src: ['*.css', '!*.min.css'],
					dest: 'css',
					ext: '.min.css'
				}]
			}
		},
		babel: {
			options: {
				sourceMap: true,
				presets: [
					['@babel/preset-env',
					{
						"targets": {
							"ie": "11"
						}
					}]
				]
			},
			dist: {
				files: {
					'js/compiled/progress-line.js': 'assets/js/progress-line.js',
					'js/compiled/pts.js': 'assets/js/pts.js',
					'js/compiled/easings.js': 'assets/js/vendor/easings.js',
					'js/compiled/navigation.js': 'assets/js/navigation.js',
					'js/compiled/theme.js': 'assets/js/theme.js',
				}
			}
		},
		concat: {
			default: {
				files: {
					'js/compiled/nano.combined.js' : [
						'assets/js/vendor/skip-link-focus-fix.js',
						'assets/js/vendor/jquery.fitvids.js',
						'js/compiled/easings.js',
						'js/compiled/navigation.js',
						'js/compiled/theme.js'
					],
					'js/compiled/pts.combined.js' : [
						'assets/js/vendor/pts.min.js',
						'js/compiled/pts.js',
					],
					'js/compiled/flickity.combined.js' : [
						'assets/js/vendor/flickity.pkgd.min.js',
						'assets/js/flickity.js',
					]
				}
			}
		},
		uglify: {
			options: {
				mangle: {
					reserved: ['jQuery']
				},
				drop_console: false,
				drop_debugger: false
			},
			default: {
				files: {
					'js/progress-line.min.js': 'js/compiled/progress-line.js',
					'js/flickity.min.js': 'js/compiled/flickity.combined.js',
					'js/nano.min.js': 'js/compiled/nano.combined.js',
					'js/pts.min.js': 'js/compiled/pts.combined.js'
				}
			}
		},
		replace: {
			styleVersion: {
				src: [
					'assets/scss/style.scss',
					'style.css'
				],
				overwrite: true,
				replacements: [{
					from: /Version:.*$/m,
					to: 'Version: <%= pkg.version %>'
				}]
			},
			functionsVersion: {
				src: [
					'functions.php'
				],
				overwrite: true,
				replacements: [ {
					from: /^define\( 'NANO_VERSION'.*$/m,
					to: 'define( \'NANO_VERSION\', \'<%= pkg.version %>\' );'
				} ]
			},
		},
		// https://www.npmjs.org/package/grunt-wp-i18n
		makepot: {
			target: {
				options: {
					domainPath: '/languages/',
					potFilename: 'nanovision.pot',
					potHeaders: {
						poedit: true, // Includes common Poedit headers.
						'x-poedit-keywordslist': true // Include a list of all possible gettext functions.
					},
					type: 'wp-theme',
					updateTimestamp: false,
					processPot: function( pot, options ) {
						pot.headers['language'] = 'en_US';
						return pot;
					}
				}
			}
		}
	});

	grunt.registerTask( 'default', [
		'sass',
		'postcss',
		'cssmin',
		'babel',
		'concat',
		'uglify'
	]);

	grunt.registerTask( 'release', [
		'replace',
		'sass',
		'postcss',
		'cssmin',
		'babel',
		'concat',
		'uglify',
		'makepot'
	]);

};