diff --git a/umap/static/umap/umap.css b/umap/static/umap/umap.css
index a7647582..c4e214b2 100644
--- a/umap/static/umap/umap.css
+++ b/umap/static/umap/umap.css
@@ -97,6 +97,7 @@ fieldset.toggle.on .more_style_options {
     height: 16px;
     margin-right: 10px;
     border: 1px solid #000;
+    background-color: DarkBlue;
 }
 
 /* **************** */