diff --git a/themes/learn2/css/custom.css b/themes/learn2/css/custom.css
index 3723658..1669663 100644
--- a/themes/learn2/css/custom.css
+++ b/themes/learn2/css/custom.css
@@ -35,5 +35,5 @@ Put your custom CSS in this file.
 /* search box placeholder text */
 #sidebar #header .searchbox input::placeholder {
     color: rgba(200, 200, 200, 0.8);
-    /*opacity: 1;*/
+    opacity: 1; /* something firefox fix */
 }