style(PdfViewer): 调整阴影透明度提升视觉效果

 <!--
  * @Date: 2025-01-21
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-10-22 15:08:11
+ * @LastEditTime: 2025-10-22 15:16:46
  * @FilePath: /mlaj/src/components/ui/PdfViewer.vue
  * @Description: PDF预览组件 - 使用pdf-vue3库
 -->
@@ -867,7 +867,7 @@ const applyPinchZoom = (newZoom, centerX, centerY, container) => {
     background: rgba(255, 255, 255, 0.15);
     padding: 12px 20px;
     border-radius: 25px;
-    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
+    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.25);
     backdrop-filter: blur(1px);
     border: 1px solid rgba(255, 255, 255, 0.3);
     transition: all 0.3s ease;