diff --git a/frontend/src/components/ImgLightbox.vue b/frontend/src/components/ImgLightbox.vue
index 73965fa..935b2c5 100644
--- a/frontend/src/components/ImgLightbox.vue
+++ b/frontend/src/components/ImgLightbox.vue
@@ -18,21 +18,21 @@ watch(
   (v) => {
     if (v) {
       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
+      prevOverflow = document.body.style.overflowY
+      // 只锁纵向：整个 overflow 改 hidden 会覆盖样式表的 overflow-x: clip，
+      // 横向从「裁剪」变「可滚动容器」，手机上整页能被拖宽（真实事故）
+      document.body.style.overflowY = 'hidden'
       document.body.classList.add('lb-open')
     } else {
       window.removeEventListener('keydown', onKey)
-      document.body.style.overflow = prevOverflow
+      document.body.style.overflowY = prevOverflow
       document.body.classList.remove('lb-open')
     }
   }
 )
 onBeforeUnmount(() => {
   window.removeEventListener('keydown', onKey)
-  document.body.style.overflow = prevOverflow
+  document.body.style.overflowY = prevOverflow
   document.body.classList.remove('lb-open')
 })