How to tell if I am on a chapter header page or on an internal page withouth the side-bar?

### Question

Using a fairly simple hierarchy I have

```
1
1.1
1.2
2.
2.1
```

If the side-bar is open the current page is highlighted and so the reader can know where she is.

What if the side-bar is closed? Is there any indication if the reader is on a chapter page (1, or 2)
or on an internal page (1.1,  1.2, 2.1 in this case)?


### Version

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