How to get second heading to show in sidebar like on docpress site?

[trusktr]

In your docs, for example, at

http://docpress.github.io/customization/markdown.html

in the sidebar I see the sub-headers in the sidebar with long dashed lines:

But on mine, I don't see the sub-headers:

I was expecting to see "HTML Buttons with Real Shadow" in the sidebar, but I don't see it. It is a second-level heading.

[trusktr]

Oh, I think I just had to restart the server, sometimes it doesn't update the menu even with manual refreshing. And sometimes some pages to hot reload, so I have to manual refresh.