Headings get shown twice in first cell of a notebook

[batpad]

Description

Steps to reproduce: In the first cell of a new notebook, convert to a Markdown cell and type the following text:

## Test heading

some text

Expected Output: Test Heading to be in an <h2> tag or so, and appear once.

Actual: Test Heading appears twice. It seems to generate an additional <h1> tag with markup like this:

<div id="skip-to-frontmatter" aria-label="article frontmatter" class="" style=""><h1 class="mb-0">Test heading</h1></div>

Screenshot of what this looks like:

Interestingly, this does not affect <h1> headings, so this issue does not affect this:

# Test heading

some text

Also, this only occurs in the first cell of a new notebook and does not affect subsequent cells.

Additional notes

I am testing this off the main branch running Jupyter lab locally. I can also see the issue present on a remote Jupyterhub running v2.3.1 .

This issue maybe the same as https://github.com/executablebooks/jupyterlab-myst/issues/222#issuecomment-2007702221 ?

cc @rowanc1

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[agoose77]

Yes, for now this only affects <h2> headings. @fwkoch do you have a feeling about whether we want to relax this and lift any heading?

[batpad]

gentle bump here .. have had a few more users complain about this .. is there anything we could do to try and help? Thanks again :-)