refs #15915 [fid_bbi] background color for selected facets

* set to brand-secondary

themes/fid_bbi/scss/compiled.scss

@@ -417,6 +417,11 @@ footer {
   background-color: $brand-primary-light;
 }
 
+//// Active Facets #15915
+.sidebar .facet.active {
+  background-color: $brand-secondary;
+}
+
 //// result body width
 .result-body {
   width: 90%;