[Feature] Use pop-up content to display footnotes content

[jiajiexiao]

Describe the feature you want 描述你的功能需求

增加侧边注支持

Discussed in https://github.com/orgs/hugo-fixit/discussions/568

^{Originally posted by jiajiexiao January 22, 2025}
How do people think about margin notes or side notes (example can be seen on this post)? I found margin notes are much more readable and helpful than footnotes and hope hugo-fixit could add this feature.

Useful reference 有价值的参考

https://capnfabs.net/posts/margin-notes-hugo-theme/
https://scottstuff.net/posts/2024/12/17/more-notes-on-notes/

[Lruihao]

@Scott Laird mentioned in More notes on notes (sidenotes, endnotes, footnotes, etc) that he changed Goldmark to Pandoc as the default Markdown renderer, which is indeed very effective in achieving the desired effect.

However, I think this is not suitable for implementation in the theme for two reasons:

1. The FixIt theme has always used Goldmark as the Markdown renderer, and this change may bring unknown destructive updates. (As a personal implementation, this may be a good way)
2. The performance on mobile terminals or tablets is not satisfactory, and there is no good compatibility method.

So I'm sorry I have to give up the implementation.

But this idea gave me a new inspiration, which is to use pop-up content to display footnote content. Just like the footnote representation in this article. I think this is a relatively more friendly way of footnote representation, and I'll try to implement it.