Remove margin/padding when layout_sidebar() is root element of a page_navbar nav_panel

Hi there.

Firstly many thanks for all the great progress on bslib. I really like the option of being able to have various page layouts within a page_navbar including some with sidebars and some without.

However, as you can currently see on your Multi-page varied layout example, when a layout_sidebar is provided as the root UI element of a nav_panel inside a page_navbar there is a noticeable amount of padding around it. I don't think this is desirable as sidebar layouts should ideally be flush to the edges of the page, like they are when a global sidebar is set in page_navbar.

Is there an easy workaround to achieve this or is possible to make this the default behaviour in the package?

Thanks!

Start with the linked Multi-page varied layout example and inspect how layout_sidebar() is nested as the root element of a page_navbar nav_panel. Reproduce the unwanted padding, then verify that the layout is flush to the page edges while global sidebar behavior remains unchanged.