Gruntfile for using SASS with Grunt and Autoprefixer for a WordPress theme with SASS init `sass/style.scss` directory

Gruntfile.js

module.exports = function(grunt) {
	grunt.initConfig({
		pkg: grunt.file.readJSON('package.json'),

		/* Autoprefixing all css files in theme root */
		autoprefixer: {
			options : {
				browsers : ['last 2 versions'],
			},
			multiple_files : {
				expand : true,
				flatten : true,
				src : '*.css',
				dest : ''
			}
		},

		/* Decompiling sass */
		sass: {
  		/* Decompiling `sass/style.scss` to HUMAN READABLE (expanded) style.dev.css */
			dev: {
				options: {
					style : 'expanded',
					sourcemap: 'none'
				},
				files: {
					'style.dev.css' : 'sass/style.scss'
				}
			},
  		/* Decompiling `sass/style.scss` to MINIFIED (compressed) style.css */
			dist: {
				options: {
					style : 'compressed',
					sourcemap: 'none'
				},
				sourcemap: 'none',
				files: {
					'style.css' : 'sass/style.scss'
				}
			}
		},

		/* Watch scss files */
		watch : {
			css: {
				files: '**/*.scss',
				tasks: [ 'sass', 'autoprefixer' ]
			}
		}
	});

	/* Load tasks */
	grunt.loadNpmTasks('grunt-autoprefixer');
	grunt.loadNpmTasks('grunt-contrib-sass');
	grunt.loadNpmTasks('grunt-contrib-watch');
	
	/* Register default task */
	grunt.registerTask('default',['watch']);
};

package.json

{
  "name": "My theme",
  "version": "0.7.0",
  "description": "My awesome theme for dudes and dudettes",
  "author": "Shramee",
  "license": "GPL-2.0+",
  "main": "index.php",
  "keywords": [
    "sass",
    "grunt",
    "autoprefixer",
    "wordpress"
  ],
  "repository": {
    "type": "git",
    "url": "https://github.com/myusername/mytheme.git"
  },
  "bugs": {
    "url": "https://github.com/myusername/mytheme/issues"
  },
  "devDependencies": {
    "grunt": "~0.4.5",
    "grunt-contrib-sass": "~1.0.0",
    "grunt-contrib-watch": "~1.0.0",
    "grunt-autoprefixer": "~3.0.4"
  },
  "dependencies": {
    "grunt": "~0.4.5",
    "grunt-autoprefixer": "~3.0.4",
    "grunt-contrib-sass": "~1.0.0",
    "grunt-contrib-watch": "~1.0.0"
  },
}