gulp.task('styles', function() {
return gulp.src('app/'+syntax+'/**/*.'+syntax+'')
.pipe(sourcemaps.init())
.pipe(sass({ outputStyle: 'expanded' }).on("error", notify.onError()))
.pipe(rename({ suffix: '.min', prefix : '' }))
.pipe(autoprefixer(['last 15 versions']))
.pipe(cleancss( {level: { 1: { specialComments: 0 } } })) // Opt., comment out when debugging
.pipe(sourcemaps.write('.'))
.pipe(gulp.dest('app/css'))
.pipe(browserSync.stream())
});
вот так нужно