[Style 0000] 修复layouts/header的层级过高的问题

src/layouts/default/header/index.vue

@@ -12,7 +12,7 @@
         'no-header': currentRoute.path.endsWith('home'),
       },
     ]"
-    style="z-index: 9999"
+    style="z-index: 1"
   >
     <!-- left start -->
     <div :class="`${prefixCls}-left`">