Update index.html

index.html

@@ -12,7 +12,7 @@
       height: 100vh;
       width: 100vw;
       font-family: 'Arial Rounded MT Bold', sans-serif;
-      background: linear-gradient(to bottom right, #ffffff, #f7e9d2);
+      background: linear-gradient(to bottom right,  #000000, #222222);
     }
 
     /* Khung chữ */