Update themes-responsive.asciidoc (#10460)

documentation/themes/themes-responsive.asciidoc

@@ -29,12 +29,14 @@ typically a layout, or the entire UI. You specify the component by the static
 
 ----
 // Have some component with an appropriate style name
+VerticalLayout l = new VerticalLayout();
+
 Label c = new Label("Here be text");
-c.addStyleName("myresponsive");
-content.addComponent(c);
+l.addStyleName("myresponsive");
+l.addComponent(c);
         
 // Enable Responsive CSS selectors for the component
-Responsive.makeResponsive(c);
+Responsive.makeResponsive(l);
 ----
 
 You can now use [literal]#++width-range++# and [literal]#++height-range++#