Simple PostCSS Gulpfile with Autoprefixer

gulpfile.js

var app = {
  paths: {
    sass: ['path/to/sass/**/*.scss'],
    css:  ['path/to/css']
  }
};

var gulp        = require("gulp"),
    gutil       = require("gulp-util"),
    sass        = require("gulp-sass"),
    rename      = require("gulp-rename"); //Not used, but u can use this to rename your files easily (e.g. *.css -> *.min.css )

gulp.task('css', [], function(){
    var postcss      = require('gulp-postcss');
    var autoprefixer = require('autoprefixer');
    return gulp.src( app.paths.sass )
        .pipe( sourcemaps.init() )
        .pipe( postcss([ autoprefixer(), cssnano() ]) )
        .pipe( sourcemaps.write('.') )
        .pipe( gulp.dest( app.paths.css ) );
});

gulp.task('css-production', ['sass'], function () {
    var postcss      = require('gulp-postcss');
    var sourcemaps   = require('gulp-sourcemaps');
    var autoprefixer = require('autoprefixer');
    var cssnano      = require("cssnano");

    return gulp.src( app.paths.sass )
        .pipe( sourcemaps.init() )
        .pipe( postcss([ autoprefixer(), cssnano() ]) )
        .pipe( sourcemaps.write('.') )
        .pipe( gulp.dest(app.paths.css) );
});

//Simple autoprefixing task for use in development, e.g. w/browser-sync
gulp.task("css", ["css"]);

//Production task, with cssnano minification
gulp.task("prod", ["css-prod"]);