Margin notes without a number

[danvonk]

Hi, Firstly thanks for the nifty filter and apologies as this is more of a user question than a bug. However, I see in the source code that MarginNotes are supported. I would like to use them without a corresponding number just as in the Tufte CSS documentation.

However, all my attempts seem to render them so far with numbers. Here's an example of my markdown file and the rendered HTML as an image:

This was one of my more touristy holidays but sometimes the tourist track isn't so bad. Here's a footnote with a number.[^1]

This is a next paragraph. But this is a margin note without a number?[^-] 

Next try^[content].

[^-]: this is a margin note.

[^1]: This is a footnote about how much I hate tourists.

The HTML equivalent from the Tufte CSS github page is after this paragraph.

<label for="mn-demo" class="margin-toggle">&#8853;</label>
<input type="checkbox" id="mn-demo" class="margin-toggle"/>
<span class="marginnote">
  This is a margin note. Notice there isn’t a number preceding the note.
</span>

Now some other unrelated paragpraph goes after.

Is rendered as:

What am I doing wrong here or is it perhaps a limitation of the filter?

Thanks