diff --git a/web/src/components/MemoContent/TaskListItem.tsx b/web/src/components/MemoContent/TaskListItem.tsx
index a76e7afe5..94545ebb3 100644
--- a/web/src/components/MemoContent/TaskListItem.tsx
+++ b/web/src/components/MemoContent/TaskListItem.tsx
@@ -38,7 +38,7 @@ export const TaskListItem: React.FC<TaskListItemProps> = ({ checked, node: _node
       // Fallback: Calculate index by counting all task list items in the entire memo
       // We need to search from the root memo content container, not just the nearest list
       // to ensure nested tasks are counted in document order
-      let searchRoot = listItem.closest('[class*="memo-content"], [class*="MemoContent"]');
+      let searchRoot = listItem.closest("[data-memo-content]");
 
       // If memo content container not found, search from document body
       if (!searchRoot) {
diff --git a/web/src/components/MemoContent/index.tsx b/web/src/components/MemoContent/index.tsx
index b60ffffe6..bcacd67f1 100644
--- a/web/src/components/MemoContent/index.tsx
+++ b/web/src/components/MemoContent/index.tsx
@@ -38,6 +38,7 @@ const MemoContent = (props: MemoContentProps) => {
     <div className={`w-full flex flex-col justify-start items-start text-foreground ${className || ""}`}>
       <div
         ref={memoContentContainerRef}
+        data-memo-content
         className={cn(
           "relative w-full max-w-full wrap-break-word text-base leading-6",
           "[&>*:last-child]:mb-0",