gulpfile.js

var gulp = require('gulp'),
    postcss = require('gulp-postcss'),
    sourcemaps = require('gulp-sourcemaps'),
    autoprefixer = require('autoprefixer'),
		customMedia = require("postcss-custom-media"),
		minmax = require('postcss-media-minmax'),
		atImport = require("postcss-import"),
		precss = require("precss"),
		postcss_for = require('postcss-for'),
    lost = require('lost');

var paths = {
  cssSource: 'src/css/',
  cssDestination: 'dist/css/'
};

gulp.task('styles', function() {
  return gulp.src(paths.cssSource + '**/*.css')
    .pipe(sourcemaps.init())
    .pipe(postcss([
			precss(),
			atImport(),
      lost(),
      autoprefixer(),
			customMedia(),
			minmax(),
			postcss_for()
    ]))
    .pipe(sourcemaps.write('./'))
    .pipe(gulp.dest(paths.cssDestination));
});

gulp.watch(paths.cssSource + '**/*.css', ['styles']);

gulp.task('default', ['styles']);