add editing mixin

apps/app/src/styles/_mixins.scss

@@ -1,6 +1,7 @@
 @use '@growi/core/scss/bootstrap/init' as bs;
 @use './variables' as var;
 
+@import './mixins/editing';
 
 @mixin apply-navigation-transition() {
   transition-timing-function: cubic-bezier(0.25, 1, 0.5, 1);

apps/app/src/styles/mixins/_editing.scss

@@ -0,0 +1,9 @@
+@mixin editing() {
+  :global {
+    .layout-root.editing {
+      :local {
+        @content;
+      }
+    }
+  }
+}