diff --git a/css/pop.css b/css/pop.css
index b3e9a13..caf8093 100644
--- a/css/pop.css
+++ b/css/pop.css
@@ -27,7 +27,7 @@ body[data-bs-theme="dark"] {
 }
 
 tr.matrix td:not(.mino) {
-    border: 2px solid transparent;
+    border: 1px solid #111;
 }
 
 .mino {