Drop libsass, use dart sass instead

[deining]

Bootstrap project has ongoing efforts, see:

• https://github.com/orgs/twbs/discussions/41370
• dart-sass 1.80.0+ throwing a lot of deprecations twbs/bootstrap#40962 - slated for v5.4 as of Oct 2025
• Drop node-sass support twbs/bootstrap#41112
• Migrate to Sass modules twbs/bootstrap#41512 (v6)

to drop node-sass support still in the 5.x branch. Since docsy is based on bootstrap, we should consider dropping libsass/node-sass in favour of dart sass, too.

Related:

• FontAwesome 7 upgrade #2314

Blocking this until there's a new release of Bootstrap using Dart Sass, be it v5.4 or v5.5 or v6.

[sumachaa]

#2226

[chalin]

@deining @sumachaa - let's track that BS issue. It seems premature to me to switch before BS has completed their "cleanup". As is mentioned in that PR, it might only land in BS v6, which means we can deal with it when we upgrade.

[chalin]

Apparently we can install via NPM, see Install Anywhere (npm) -- I like that option for our projects.

npm install -g sass

However, please note that this will install the pure JavaScript implementation of Sass, which runs somewhat slower than the other options listed here. But it has the same interface, so it’ll be easy to swap in another implementation later if you need a bit more speed!

[jmooring]

install via NPM

See https://github.com/sass/dart-sass?tab=readme-ov-file#embedded-dart-sass.

The --embedded command-line flag is not available when you install Dart Sass as an npm package.

This may change at some point. See sass/dart-sass#2413.

[chalin]

I've added some references to the opening comment. As I mention there, I propose that we block this until there's a BS release using Dart Sass. Btw, thanks for pointing out the limitations of an NPM installation @jmooring.