fix for table borders hidden behind background in Firefox

css/chess.css

@@ -65,6 +65,11 @@ button:disabled .silhouette {
 	 position: relative;
 }
 
+#cb_board td {
+	 background-clip: padding-box;
+	 position: relative;
+}
+
 #cb_light_name, #cb_dark_name {
 	 width: 8em;
 }