How to use figure-md directive

[tomkivlin]

I am trying to change from raw html to MyST directives and am trying use the figure-md directive (I have added colon_fence to the enabled extensions for MyST).

In the example here: https://myst-parser.readthedocs.io/en/latest/syntax/optional.html#markdown-figures, the caption appears directly underneath the image, aligned with the image. This is what I'd expect have read the documentation on that directive.

However, when I apply the following code, the caption is not aligned, and I'm struggling to work out why.

:::{figure-md} figure-1
:class: myclass
<img src="figures/figure-1-test.png" alt="Figure showing something" width="100%"/>

This is my caption - it is not aligned
:::

If I inspect the generated page, I see the following, so I'm wondering why it's not being aligned?

<figure class="myclass align-default" id="figure-1">
<a class="reference internal image-reference" href="../_images/figure-1-test.png"><img alt="Figure showing something" src="../_images/figure-1-test.png" style="width: 100%;"/></a>
<figcaption>
<p><span class="caption-text">This is my caption - it is not aligned</span><a class="headerlink" href="#figure-1" title="Permalink to this image">¶</a></p>
</figcaption>
</figure>

Any ideas?