diff --git a/browser/themes/shared/customizableui/customizeMode.css b/browser/themes/shared/customizableui/customizeMode.css
index b3ee1ada6cbaef46ade98323d43bf72d84db3b88..a87a7511ba19d02849d1ccab487684156f7d8698 100644
--- a/browser/themes/shared/customizableui/customizeMode.css
+++ b/browser/themes/shared/customizableui/customizeMode.css
@@ -547,3 +547,15 @@ toolbarpaletteitem > #search-container > #searchbar > .searchbar-textbox {
   80% { border-color: rgb(20,155,249); color: rgb(20,155,249); }
   100% { border-color: rgb(195,17,206); color: rgb(195,17,206); }
 }
+
+#customization-zen-browser-space {
+  width: 200px;
+  height: 5px;
+}
+
+#zen-customization-uidensity-separator {
+  height: 100%;
+  width: 1px;
+  margin: 0 5px;
+  border-left: 1px solid rgba(0,0,0,.15);
+}