style: center header navigation vertically

- Change nav alignment from flex-end to center
- Remove padding-bottom
- Set height to 80px (full header height)
- Navigation text now vertically centered

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

src/components/Header.vue

@@ -197,11 +197,9 @@ export default {
 
 #header .header-nav .header-nav-wrapper {
   float: right;
-  height: 50px;
+  height: 80px;
   display: flex;
-  align-items: flex-end;
-  padding-bottom: 15px;
-  box-sizing: border-box;
+  align-items: center;
 }
 
 /* 导航栏 每个导航 */