diff --git a/shiny/express/_run.py b/shiny/express/_run.py
index cf3db87ad..9ad1736c1 100644
--- a/shiny/express/_run.py
+++ b/shiny/express/_run.py
@@ -19,7 +19,7 @@
 
 __all__ = ("wrap_express_app",)
 
-_DEFAULT_PAGE_FUNCTION = ui.page_fluid
+_DEFAULT_PAGE_FUNCTION = ui.page_fillable
 
 
 def wrap_express_app(file: Path) -> App: