diff --git a/packages/genui/a2ui/styles/catalog/Modal.css b/packages/genui/a2ui/styles/catalog/Modal.css
index f9e7563fa9..5c3986669e 100644
--- a/packages/genui/a2ui/styles/catalog/Modal.css
+++ b/packages/genui/a2ui/styles/catalog/Modal.css
@@ -13,6 +13,7 @@
   align-items: center;
   justify-content: center;
   padding: 20px;
+  inset: 0;
   box-sizing: border-box;
 }