Миша

gulp.task('scss', function () {
    return gulp.src('app/scss/main.scss')
        .pipe(scss()).on('error', notify.onError())
        .pipe(autoprefixer({
            browsers: ['last 15 versions'],
            cascade: false
        }))
        .pipe(gulp.dest('app/css'))
        .pipe(browserSync.stream());
});

gulp.task('csscomb', ['scss'], function () {
    return gulp.src('app/css/main.css')
        .pipe(csscomb('configs/yandex.json'))
        .pipe(gulp.dest('app/css'));
});

gulp.task('cssnano', ['csscomb'], function () {
    return gulp.src('app/css/main.css')
        .pipe(cssnano())
        .pipe(rename({suffix: '.min'}))
        .pipe(gulp.dest('dist/css'));
});

gulp.task('build', gulpSequence('clean', ['cssnano', 'scripts', 'useref', 'img']));