change icon-plus size

packages/app/src/styles/_page-tree.scss

@@ -5,6 +5,13 @@ $grw-pagetree-item-padding-left: 10px;
 .grw-pagetree {
   min-height: calc(100vh - ($grw-navbar-height + $grw-navbar-border-width + $grw-sidebar-content-header-height + $grw-sidebar-content-footer-height));
 
+  .btn-page-item-control {
+    .icon-plus::before {
+      width: 18px;
+      height: 18px;
+    }
+  }
+
   .list-group-item {
     .grw-visible-on-hover {
       display: none;