gulpfile.js

gulp.task('build-stylesheets', function () {
    return gulp.src('sources/stylesheets/tenside.less')
        .pipe(plumber())
        .pipe(sourcemaps.init())
        .pipe(less({compress: true}))
        .pipe(autoprefixer({
            browsers: ['last 2 versions'],
            cascade: false
        }))
        .pipe(rename({suffix:'.min'}))
        .pipe(sourcemaps.write('.', {sourceRoot: '../sources/stylesheets'}))
        .pipe(gulp.dest('stylesheets'));
});