Scrollbar disappears when sidebar is short

[jsha]

In this example, for ToString, the sidebar is shorter than the page, so there is no scrollbar:

In this example, for String, the sidebar is longer so there is a scrollbar:

The problem here is that the scrollbar forms part of the visual layout of the page, separating the sidebar from the main content. I think for the sake of consistency we should always show the sidebar.

[GuillaumeGomez]

I think this is a good idea. I'll send a PR for it.