frontend CHANGE use Material library to show loading in progress
diff --git a/frontend/config/tree.component.scss b/frontend/config/tree.component.scss
index 72e5ad2..a125480 100644
--- a/frontend/config/tree.component.scss
+++ b/frontend/config/tree.component.scss
@@ -127,3 +127,7 @@
         color: $colorTextInverse;
     }
 }
+
+.loading {
+	margin-top: 0.5em;
+}