diff --git a/themes/garland/style.css b/themes/garland/style.css
index e8b20023697..5588662eadd 100644
--- a/themes/garland/style.css
+++ b/themes/garland/style.css
@@ -324,6 +324,11 @@ table .form-button, table .form-submit {
   margin-bottom: 0;
 }
 
+/* Prevent the previous directive from showing the content of script elements in Mozilla browsers. */
+#header-region script {
+  display: none;
+}
+
 #header-region p, #header-region img {
   margin-top: 0.5em;
 }