pidgin/nest

Update to hugo-theme-learn 2.5.0

18 months ago, Elliott Sales de Andrade
50afdb25d25a
Update to hugo-theme-learn 2.5.0

The latest version improves compatibility with latest Hugo and adds several enhancements. This enables us to drop most of our vendored copies of the theme files.

* Mermaid is now a theme option, so we don't need to overlay a copy of the partial with it removed.
* Custom CSS has a theme option to load it, so we don't need to add it to `custom-header.html`.
* It now uses the [recommended colour style variant customization](https://learn.netlify.app/en/basics/style-customization/#yours-variant) instead of copying the theme's CSS. Most of the sidebar seemed unchanged from the default, but I copied them anyway to prevent them changing.
* Dropping the copy of the theme CSS means moving our customized fixed-max-width style on the body to the custom CSS.
* I moved the footer into `custom-footer.html` so that most partials would not need to be copied; this does mean it's no longer a bubble that's the width of the content, but I always found that weird anyway. Some new CSS is necessary to make it centred properly.
* I found many of the partials and the JavaScript were functionally the same as the original theme's copy, so I removed them.

Testing Done:
Opened up a few pages and saw things were roughly equivalent, except the footer as noted above.

The only regression I believe is that the ToC is no longer automatically added on 'long' pages. However, it's still there on hover of the ToC icon.

Reviewed at https://reviews.imfreedom.org/r/1933/
hugo/themes/**/*
hugo/archetypes/**/*