implemented warning message(only the design)

src/client/js/components/PageDuplicateModal.jsx

@@ -133,8 +133,14 @@ const PageDuplicateModal = (props) => {
             { t('modal_duplicate.label.Duplicate with child') }
           </label>
           <div>
-            <ul>
-              {isDuplicateRecursively && subordinatedPaths.map(duplicatedNewPath => <li key={duplicatedNewPath}>{duplicatedNewPath}</li>)}
+            <ul className="duplicate-name">
+              {isDuplicateRecursively && subordinatedPaths.map((duplicatedNewPath) => {
+                  if (true) {
+                    return <li className="duplicate-exist" key={duplicatedNewPath}>{duplicatedNewPath}: Same page already exists</li>;
+                  }
+                  return <li key={duplicatedNewPath}>{duplicatedNewPath}</li>;
+                })
+              }
             </ul>
           </div>
           <div> {getSubordinatedError} </div>

src/client/styles/scss/_page_duplicate_modal.scss

@@ -0,0 +1,7 @@
+.duplicate-name {
+  list-style: none;
+}
+
+.duplicate-exist {
+  color: #c7254e;
+}

src/client/styles/scss/style-app.scss

@@ -47,6 +47,7 @@
 @import 'navbar_kibela';
 @import 'notification';
 @import 'on-edit';
+@import 'page_duplicate_modal';
 @import 'page_list';
 @import 'page-path';
 @import 'page';