Interim working solution

style.css

@@ -445,3 +445,26 @@ input[type="radio"]:checked {
 input[type="radio"]:focus {
     outline: none;
 }
+
+/* In-Box Error Message */
+.qr-error-msg {
+    color: red;
+    font-family: var(--font-mono);
+    font-weight: 700;
+    text-align: center;
+    text-transform: uppercase;
+    font-size: 0.9rem;
+    line-height: 1.4;
+    
+    /* Brutalist Box inside the Box */
+    border: 2px solid red;
+    padding: 1rem;
+    background-color: #fff;
+    width: 80%; /* Don't touch the edges */
+}
+
+/* Ensure the container keeps its shape even when showing error */
+#qr-container {
+    /* Existing styles... */
+    position: relative; /* Just in case */
+}