Headings and toctree children mixing in left sidebar nav

[theletterf]

I'm using the Alabaster theme with Sphinx 4.1.0. When I create a page like the following, with the toctree on top...

.. toctree::
   :hidden:
  
   page1
   page2
   page3

Heading1
==============================

Some text

...the heading links appear underneath the toctree items in the nav, like this:

Title of the page
     page1
     page2
     page3
     Heading1

If I put the toctree at the end of the page, the toctree item become children of the heading before:

Title of the page 
     Heading1
          page1
          page2
          page3

Other times put the headings in a separate in-page ToC layer, usually to the right side. That's not available in Alabaster, but then again, is there a way of properly showing the toctree children pages as subpages instead than in-page ToC headings?