diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/ApiKeys.razor b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/ApiKeys.razor
index ec88539f..bbf436e8 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/ApiKeys.razor
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/ApiKeys.razor
@@ -142,6 +142,13 @@
         try
         {
             _keys = await Keys.ListAsync(default);
+            // The one-time banner is only meaningful while its key exists; the credential is
+            // otua_<keyId>_<secret>, so drop it once no listed key matches (deleted here or elsewhere).
+            if (_created is not null
+                && !_keys.Any(k => _created.StartsWith($"otua_{k.ApiKeyId}_", StringComparison.Ordinal)))
+            {
+                _created = null;
+            }
         }
         catch (Exception ex)
         {
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/wwwroot/css/site.css b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/wwwroot/css/site.css
index 3e5c1edb..b9c3edd7 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/wwwroot/css/site.css
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/wwwroot/css/site.css
@@ -48,3 +48,22 @@
     flex: 0 0 18px;
     width: 18px;
 }
+
+/* Modal sizing (#631). Bootstrap sizes .modal-backdrop with 100vw/100vh, and 100vw includes the
+   scrollbar gutter, so on a tall form (Configure driver / Modbus) the backdrop overran the viewport
+   and produced a page-level horizontal scrollbar. Pin it with inset:0 instead (no vw/vh), and keep
+   the dialog inside the viewport. These modals are hand-rolled (display:block, no Bootstrap JS). */
+.modal-backdrop {
+    inset: 0;
+    width: auto;
+    height: auto;
+}
+
+.modal {
+    overflow-x: hidden;
+    overflow-y: auto;
+}
+
+.modal-dialog {
+    max-width: min(var(--bs-modal-width, 500px), calc(100vw - 2rem));
+}