diff --git a/frontend/components/StackModal.tsx b/frontend/components/StackModal.tsx
index 3b4696a..e8a18c4 100644
--- a/frontend/components/StackModal.tsx
+++ b/frontend/components/StackModal.tsx
@@ -38,11 +38,11 @@ export const StackModal: React.FC<{ isOpen: boolean; onClose: () => void; root:
   const canBack = stack.length > 1;
 
   return (
-    <div className="fixed inset-0 bg-black/40 z-[70] flex items-end sm:items-center justify-center sm:p-4">
+    <div className={`fixed inset-0 bg-black/40 z-[70] flex items-end sm:items-center justify-center ${fullscreen ? '' : 'sm:p-4'}`}>
       <div
         className={`bg-white shadow-2xl flex flex-col overflow-hidden transition-all duration-300 w-full ${
           fullscreen
-            ? 'h-dvh max-h-none rounded-none sm:w-screen'
+            ? 'h-full rounded-none'
             : 'max-h-[90vh] rounded-t-2xl sm:w-[440px] sm:max-w-[95vw] sm:h-auto sm:max-h-[88vh] sm:rounded-3xl'
         }`}
       >