fix z-index

@@ -171,7 +171,7 @@ gulp.task('font', () => {
 gulp.task('postcss', ['assets'], () => {
 gulp.task('postcss', ['assets'], () => {
     return gulp.src(['scss/base.css', 'scss/*/_index.css', '!scss/plugin/*', '!scss/common/*'])
     return gulp.src(['scss/base.css', 'scss/*/_index.css', '!scss/plugin/*', '!scss/common/*'])
         .pipe(postcss(postcssPlugin(env.pro)))
         .pipe(postcss(postcssPlugin(env.pro)))
-        .pipe(cssnano())
+        .pipe(cssnano({zindex: false }))
         .pipe(rename((cssPath) => {
         .pipe(rename((cssPath) => {
             if (cssPath.dirname === '.') {
             if (cssPath.dirname === '.') {
                 return;
                 return;