diff --git a/src/components/ErrorMessage.vue b/src/components/ErrorMessage.vue
index d250537b..c45e606a 100644
--- a/src/components/ErrorMessage.vue
+++ b/src/components/ErrorMessage.vue
@@ -22,6 +22,7 @@ export default {
     border: 2px solid var(--color-danger);
     border-radius: 2px;
     padding: 5px 10px;
-    margin: 20px 0;
+    max-width: var(--grid-max-width);
+    margin: 20px auto;
   }
 </style>
diff --git a/src/components/MainWindow.vue b/src/components/MainWindow.vue
index a379c68e..ee0f0e1f 100644
--- a/src/components/MainWindow.vue
+++ b/src/components/MainWindow.vue
@@ -8,7 +8,7 @@
 </template>
 
 <script>
-import { createNamespacedHelpers, mapGetters } from 'vuex';
+import { mapGetters, mapState } from 'vuex';
 
 import EditorPlaylist from './EditorPlaylist.vue';
 import ErrorMessage from './ErrorMessage.vue';
@@ -16,8 +16,6 @@ import StartTimeSettings from './StartTimeSettings.vue';
 import MainWindowHeader from './MainWindowHeader.vue';
 import EditorOperationPanel from './EditorOperationPanel.vue';
 
-const { mapState } = createNamespacedHelpers('editor');
-
 export default {
   name: 'MainWindow',
   components: {