fix: set fixed banner height for all screen sizes

- Desktop (>996px): height: 500px
- Tablet (768px-996px): height: 400px (was: auto)
- Mobile (<768px): height: 300px (was: auto)
- Prevents layout collapse and white gaps

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

src/view/HomePage.vue

@@ -325,7 +325,7 @@ export default {
 /* 媒体查询（手机） */
 @media screen and (max-width: 768px) {
   #swiper {
-    height: auto;
+    height: 300px;
   }
 
   #swiper .banner-swiper .swiper-slide-title > h1 {
@@ -431,7 +431,7 @@ export default {
 /* 媒体查询（平板） */
 @media screen and (min-width: 768px) and (max-width: 996px) {
   #swiper {
-    height: auto;
+    height: 400px;
   }
 
   #swiper .banner-swiper .swiper-slide-title > h1 {