visionOS sidebar like Safari in the visionOS simulator

Does anyone know how to create a sidebar like Safari in the visionOS simulator where the web content does not change size and the sidebar opens by sliding out from behind the content? Everything I have tried opens the sidebar in the same window and makes the content smaller. I tried making the sidebar as an ornament, but that didn't feel like the right solution.

You can see in this screenshot that the sidebar is coming out from behind the content. It is not an ornament on the side of the content. It is also at the same z level as the content.