diff --git a/css/chess.css b/css/chess.css
index 1761774..2796c02 100644
--- a/css/chess.css
+++ b/css/chess.css
@@ -91,6 +91,7 @@ body > #page {
 input.image-checkbox {
    display: inline-block;
    -webkit-appearance: none;
+   -moz-appearance: none;
    appearance: none;
    padding: 0;
    margin: 0;