fix: remove gap between header and banner

- Reduce header-nav-wrapper height from 80px to 50px
- Total height (50px + 15px padding-bottom) = 65px matches logo visual bottom
- Prevents extra whitespace at bottom of header

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

src/components/Header.vue

@@ -197,7 +197,7 @@ export default {
 
 #header .header-nav .header-nav-wrapper {
   float: right;
-  height: 80px;
+  height: 50px;
   display: flex;
   align-items: flex-end;
   padding-bottom: 15px;