added upload uboot

web/style.css

@@ -146,6 +146,21 @@ h2 {
     text-align: center;
 }
 
+.upload-hint {
+    margin: 15px 0;
+    padding: 12px;
+    background: rgba(255, 165, 0, 0.15);
+    border: 1px solid rgba(255, 165, 0, 0.5);
+    border-radius: 8px;
+    color: #ffa500;
+    font-size: 0.9rem;
+    display: none;
+}
+
+.upload-hint.visible {
+    display: block;
+}
+
 .file-input-wrapper {
     margin-bottom: 20px;
 }