gulpfile.js

gulp.task('sass', function() {
  browserSync.notify('<span style="color: grey">Running:</span> Sass compiling');
  return gulp.src(paths.sass)
    .pipe(sass({
      bundleExec: true,
      style: 'expanded',
      onError: browserSync.notify
    }))
    .pipe(prefix("last 2 versions", "> 1%"))
    .pipe(gulp.dest('_src/css'))
    .pipe(cssmin())
    .pipe(gulp.dest(paths.assets))
    .pipe(browserSync.reload({stream:true}));;
});