diff --git a/src/textual/app.py b/src/textual/app.py
index d0ad7962f2..5fb81038cc 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -2248,6 +2248,7 @@ def switch_mode(self, mode: str) -> AwaitMount:
             await_mount = AwaitMount(self.screen, [])
 
         self._current_mode = mode
+        self.refresh_css()
         self.screen._screen_resized(self.size)
         self.screen.post_message(events.ScreenResume())