gulpfile.js

'use strict';

var gulp = require('gulp');
var sass = require('gulp-sass');
var sourcemaps = require('gulp-sourcemaps');
var cleanCSS = require('gulp-clean-css');
var autoprefixer = require('gulp-autoprefixer');

gulp.task('sass', function () {
  return gulp.src('./assets/sass/main.scss')
    .pipe(sourcemaps.init())
    .pipe(sass().on('error', sass.logError))
    .pipe(autoprefixer({
            browsers: ['last 4 versions'],
            cascade: false
        }))
    .pipe(sourcemaps.write('/', {
      includeContent: false,
      sourceRoot: '/'
    }))
    .pipe(gulp.dest('./_site/assets/css'));
});

gulp.task('sass:watch', function () {
  gulp.watch('./assets/sass/**/*.scss', ['sass']);
});

gulp.task('sass:prod', function () {
  return gulp.src('./assets/sass/main.scss')
    .pipe(sass().on('error', sass.logError))
    .pipe(autoprefixer({
            browsers: ['last 4 versions'],
            cascade: false
        }))
    .pipe(cleanCSS({compatibility: 'ie8'}))
    .pipe(gulp.dest('./assets/css'));
});

gulp.task('default', [ 'sass:watch' ]);

gulp.task('css', [ 'sass:prod' ]);