Modified list of folders to delete after building

gulpfile.js

@@ -100,14 +100,17 @@ gulp.task('build', ['concat-css', 'concat-js', 'min-html']);
 gulp.task('clean', ['build'], function () {
     return del([
         paths.cssDir,
-        paths.cssOut,
+        paths.cssOut + '/**/*.css',
+        '!' + paths.cssOut,
         '!' + paths.cssOut + '/style.all.min.css',
 
         paths.jsDir,
-        paths.jsOut,
+        paths.jsOut + '/**/*.js',
+        '!' + paths.jsOut,
         '!' + paths.jsOut + '/script.all.min.js',
 
-        paths.lessDir
+        paths.lessDir,
+        paths.lessOut
     ]);
 });