style(HomePage): 调整z-index值以提高页面布局可读性

将自定义标签导航的z-index值从999调整为9，以避免与其他元素的层叠冲突，提升页面布局的可读性和一致性

 <!--
  * @Date: 2025-03-20 19:55:21
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-03-25 17:52:17
+ * @LastEditTime: 2025-03-25 18:05:48
  * @FilePath: /mlaj/src/views/HomePage.vue
  * @Description: 亲子学院首页组件
  *
@@ -255,7 +255,7 @@
       </div>
 
       <!-- Custom Tab Navigation -->
-      <div class="sticky top-0 bg-white/70 backdrop-blur-lg" style="z-index: 999;">
+      <div class="sticky top-0 bg-white/70 backdrop-blur-lg" style="z-index: 9;">
         <div class="px-4 border-b border-gray-200">
           <div class="flex space-x-6">
             <button