Forgotten resource!

P/Sda1/InsertGui/V12/src/main/webapp/VAADIN/themes/mytheme/styles.scss

+@import "mytheme.scss";
+@import "addons.scss";
+
+// This file prefixes all rules with the theme name to avoid causing conflicts with other themes.
+// The actual styles should be defined in mytheme.scss
+
+.mytheme {
+  @include addons;
+  @include mytheme;
+
+}