diff --git a/src/app.rs b/src/app.rs
index 750f108e31f..9b3e2e18d3f 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -20,6 +20,25 @@ where
         App { scope }
     }
 
+    /// Alias to `mount_in_place` taking a component having a body element at the
+    /// root of the HTML generated by its `view` method. Use this method when you
+    /// need to manipulate the body element. For example, adding/removing app-wide
+    /// CSS classes of the body element.
+    pub fn replace_body(self) -> Scope<COMP> {
+        let html_element = document()
+            .query_selector("html")
+            .expect("can't get html node for rendering")
+            .expect("can't unwrap html node");
+        let body_element = document()
+            .query_selector("body")
+            .expect("can't get body node for rendering")
+            .expect("can't unwrap body node");
+        html_element
+            .remove_child(&body_element)
+            .expect("can't remove body child");
+        self.scope.mount_in_place(html_element, None, None, ())
+    }
+
     /// Alias to `mount("body", ...)`.
     pub fn mount_to_body(self) -> Scope<COMP> {
         // Bootstrap the component for `Window` environment only (not for `Worker`)