diff --git a/frontend/src/components/ImgLightbox.vue b/frontend/src/components/ImgLightbox.vue
index 0755673..73965fa 100644
--- a/frontend/src/components/ImgLightbox.vue
+++ b/frontend/src/components/ImgLightbox.vue
@@ -20,15 +20,20 @@ watch(
       window.addEventListener('keydown', onKey)
       prevOverflow = document.body.style.overflow
       document.body.style.overflow = 'hidden'
+      // 吸顶栏带 backdrop-filter，真机上其合成层会盖在遮罩之上
+      // （遮罩明明 z-index 更高也拦不住）——索性开预览时整个藏掉
+      document.body.classList.add('lb-open')
     } else {
       window.removeEventListener('keydown', onKey)
       document.body.style.overflow = prevOverflow
+      document.body.classList.remove('lb-open')
     }
   }
 )
 onBeforeUnmount(() => {
   window.removeEventListener('keydown', onKey)
   document.body.style.overflow = prevOverflow
+  document.body.classList.remove('lb-open')
 })
 
 // 手机滑动翻页：横向位移超 44px 且大于纵向位移才算一次滑动
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index 6f53ca6..5cbb2bb 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -1452,6 +1452,12 @@ a.cm-name-a:hover {color: var(--accent);}
 .admin-shell .image-resize-handle {opacity: 0.45;}
 .admin-shell .image-wrapper:hover .image-resize-handle {opacity: 1;}
 
+/* lightbox 打开时藏掉吸顶/固定栏：一是全屏观感，二是绕开真机上
+   backdrop-filter 元素合成层盖过遮罩的 Chromium 绘制问题 */
+body.lb-open .sticky-head,
+body.lb-open .topbar,
+body.lb-open .reading-bar {visibility: hidden;}
+
 /* classic 文章页阅读进度条：视口顶部细线，vivid 的同款能力 */
 .reading-bar {position: fixed;
   top: 0;