diff --git a/web/components/confirm-dialog.tsx b/web/components/confirm-dialog.tsx
index 688a936..0034e13 100644
--- a/web/components/confirm-dialog.tsx
+++ b/web/components/confirm-dialog.tsx
@@ -41,6 +41,19 @@ export default function ConfirmDialog({
     }
   }, [open]);
 
+  // Lock body scroll while open. Native <dialog> doesn't do this in all
+  // browsers (notably iOS Safari), so background scroll can leak through
+  // when scrolling on the dialog content. We restore the previous value
+  // on close so other modals stacking later don't regress this.
+  useEffect(() => {
+    if (!open) return;
+    const previous = document.body.style.overflow;
+    document.body.style.overflow = "hidden";
+    return () => {
+      document.body.style.overflow = previous;
+    };
+  }, [open]);
+
   return (
     <dialog
       ref={ref}
diff --git a/web/components/form-dialog-shell.tsx b/web/components/form-dialog-shell.tsx
index f6b8aef..9b325a4 100644
--- a/web/components/form-dialog-shell.tsx
+++ b/web/components/form-dialog-shell.tsx
@@ -40,6 +40,16 @@ export default function FormDialogShell({
     else if (!open && dialog.open) dialog.close();
   }, [open]);
 
+  // Lock body scroll while open (native <dialog> doesn't on iOS Safari).
+  useEffect(() => {
+    if (!open) return;
+    const previous = document.body.style.overflow;
+    document.body.style.overflow = "hidden";
+    return () => {
+      document.body.style.overflow = previous;
+    };
+  }, [open]);
+
   return (
     <dialog
       ref={ref}