Convert Definition Lists (<dl>) to Frames (<fieldset>)

Yihui Xie 2023-11-07

When I suggested a department chair in 2019 that they may consider opening a blog so that all students and faculty in the department can write together (which sounded exciting to me), he expressed a concern that some readers might remember authors’ mistakes in the posts. Considering the reputation of the whole department, that is a valid concern. However, to err is human (and to forgive is divine). Everyone makes mistakes. I often update my old posts to correct mistakes or write a note saying certain information is oudated after a few years.

My notes did not have a formal form. Sometimes a note may be a blockquote, and sometimes it is just a normal paragraph. Today I was thinking how I could make them more consistent. One constraint is that it would be nice if I could express it in pure Markdown. Unfortunately, CommonMark does not support fenced Divs, otherwise I would use a fenced Div like:

::: Note
This post is outdated. Please ignore it.

Eventually I decided to hack at definition lists. A note will be like:

Update on 2023-11-09

:   Please ignore this post. The method no longer works.

This will render to the HTML tag <dl> (with <dt> and <dd> inside).

Next I started to think about styling, and recalled the <fieldset> tag that I learned sixteen years ago.1 With a few lines of JavaScript, I was able to change <dl> to <fieldset>. Below is a demo:

Notice on 2023-11-07

Thank you for noticing this new notice!

Your noticing it has been noted, and will be reported to the authorities.

If you want to use my JS code, you can load it via:

<script src="" defer></script>

Then you only need to write Markdown:


:   Content

which will be rendered to HTML:


Then my JS code will convert it to:


Mission complete.

  1. See? This is why you should blog—things you learned, no matter how long ago, will not be wasted. ↩︎