feat: 导航栏滚动时半透明毛玻璃效果

- 顶部时完全透明
- 滚动 >10px 后渐变为半透明毛玻璃 (0.75 透明度 + blur)
- CSS transition 平滑过渡

common/common.css

@@ -76,11 +76,19 @@ body {
   left: 0;
   width: 100%;
   z-index: 9999;
-  /* 深色毛玻璃 Header，与下拉菜单统一风格 */
-  background: rgba(10, 12, 22, 0.92);
-  backdrop-filter: blur(16px);
-  -webkit-backdrop-filter: blur(16px);
-  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.06);
+  background: transparent;
+  backdrop-filter: none;
+  -webkit-backdrop-filter: none;
+  box-shadow: none;
+  transition: background 0.3s ease, backdrop-filter 0.3s ease, box-shadow 0.3s ease;
+}
+
+/* 滚动后变半透明毛玻璃 */
+.nav-shadow.scrolled {
+  background: rgba(10, 12, 22, 0.75);
+  backdrop-filter: blur(20px);
+  -webkit-backdrop-filter: blur(20px);
+  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.04);
 }
 
 .nav-header {

common/common.js

@@ -126,6 +126,16 @@ $(function () {
     location.href = url;
   };
   function initHeader() {
+    // 滚动时导航栏变半透明毛玻璃
+    var navShadow = document.querySelector('.nav-shadow');
+    window.addEventListener('scroll', function () {
+      if (window.scrollY > 10) {
+        navShadow.classList.add('scrolled');
+      } else {
+        navShadow.classList.remove('scrolled');
+      }
+    });
+
     let showIndex = 0;
     let hoverTimer = null;
     let leaveTimer = null;