Add Dart Sass installation and usage documentation

Closes gohugoio#1921

content/en/hugo-pipes/transpile-sass-to-css.md

@@ -0,0 +1,211 @@
+---
+title: ToCSS
+linkTitle: Transpile Sass to SCSS
+description: Transpile Sass to CSS.
+categories: [asset management]
+keywords: []
+menu:
+  docs:
+    parent: pipes
+    weight: 30
+weight: 02
+signature: ["resources.ToCSS RESOURCE [OPTIONS]", "toCSS RESOURCE [OPTIONS]"]
+toc: true
+aliases: [/hugo-pipes/transform-to-css/]
+---
+
+## Usage
+
+Transpile Sass to CSS using the LibSass transpiler included in Hugo's extended edition, or [install Dart Sass](#dart-sass) to use the latest features of the Sass language.
+
+```go-html-template
+{{ $options := dict "transpiler" "libsass" "targetPath" "css/style.css" }}
+{{ with resources.Get "sass/main.scss" | toCSS $options | minify | fingerprint }}
+  <link rel="stylesheet" href="{{ .RelPermalink }}" integrity="{{ .Data.Integrity }}" crossorigin="anonymous">
+{{ end }}
+```
+
+Sass has two forms of syntax: [SCSS] and [indented]. Hugo supports both.
+
+[scss]: https://sass-lang.com/documentation/syntax#scss
+[indented]: https://sass-lang.com/documentation/syntax#the-indented-syntax
+
+
+## Options
+
+transpiler
+: (`string`) The transpiler to use, either `libsass` (default) or `dartsass`. Hugo's extended edition includes the LibSass transpiler. To use the Dart Sass transpiler, see the [installation instructions](#dart-sass) below.
+
+targetPath
+: (`string`) If not set, the transformed resource's target path will be the original path of the asset file with its extension replaced by `.css`.
+
+vars {{< new-in "0.109.0" >}}
+: (`map`) A map of key/value pairs that will be available in the `hugo:vars` namespace. Useful for [initializing Sass variables from Hugo templates](https://discourse.gohugo.io/t/42053/).
+
+```scss
+// LibSass
+@import "hugo:vars";
+
+// Dart Sass
+@use "hugo:vars" as v;
+```
+
+outputStyle
+: (`string`) Output styles available to LibSass include `nested` (default), `expanded`, `compact`, and `compressed`. Output styles available to Dart Sass included `expanded` (default) and `compressed`.
+
+precision
+: (`int`) Precision of floating point math. Not applicable to Dart Sass.
+
+enableSourceMap
+: (`bool`) If `true`, generates a source map.
+
+sourceMapIncludeSources {{< new-in "0.108.0" >}}
+: (`bool`) If `true`, embeds sources in the generated source map. Not applicable to LibSass.
+
+includePaths
+: (`slice`) A slice of paths, relative to the project root, that the transpiler will use when resolving `@use` and `@import` statements.
+
+```go-html-template
+{{ $options := dict
+  "transpiler" "dartsass"
+  "targetPath" "css/style.css"
+  "vars" site.Params.styles
+  "enableSourceMap" (not hugo.IsProduction) 
+  "includePaths" (slice "node_modules/bootstrap/scss")
+}}
+{{ with resources.Get "sass/main.scss" | toCSS $options | minify | fingerprint }}
+  <link rel="stylesheet" href="{{ .RelPermalink }}" integrity="{{ .Data.Integrity }}" crossorigin="anonymous">
+{{ end }}
+```
+
+## Dart Sass
+
+The extended version of Hugo includes [LibSass] to transpile Sass to CSS. In 2020, the Sass team deprecated LibSass in favor of [Dart Sass].
+
+Use the latest features of the Sass language by installing Dart Sass in your development and production environments.
+
+### Installation overview
+
+Dart Sass is compatible with Hugo v0.114.0 and later.
+
+If you have been using Embedded Dart Sass[^1] with Hugo v0.113.0 and earlier, uninstall Embedded Dart Sass, then install Dart Sass. If you have installed both, Hugo will use Dart Sass.
+
+If you install Hugo as a [Snap package] there is no need to install Dart Sass. The Hugo Snap package includes Dart Sass.
+
+[^1]: In 2023, the Sass team deprecated Embedded Dart Sass in favor of Dart Sass.
+
+### Installing in a development environment
+
+When you install Dart Sass somewhere in your PATH, Hugo will find it.
+
+OS|Package manager|Site|Installation
+:--|:--|:--|:--
+Linux|Homebrew|[brew.sh]|`brew install sass/sass/sass`
+Linux|Snap|[snapcraft.io]|`sudo snap install dart-sass`
+macOS|Homebrew|[brew.sh]|`brew install sass/sass/sass`
+Windows|Chocolatey|[chocolatey.org]|`choco install sass`
+Windows|Scoop|[scoop.sh]|`scoop install sass`
+
+You may also install [prebuilt binaries] for Linux, macOS, and Windows.
+
+Run `hugo env` to list the active transpilers.
+
+### Installing in a production environment
+
+For [CI/CD] deployments (e.g., GitHub Pages, GitLab Pages, Netlify, etc.) you must edit the workflow to install Dart Sass before Hugo builds the site[^2]. Some providers allow you to use one of the package managers above, or you can download and extract one of the prebuilt binaries.
+
+[^2]: You do not have to do this if (a) you have not modified the assets cache location, and (b) you have not set `useResourceCacheWhen` to `never` in your [site configuration], and (c) you add and commit your resources directory to your repository.
+
+#### GitHub Pages
+
+To install Dart Sass for your builds on GitHub Pages, add this step to the GitHub Pages workflow file:
+
+```yaml
+- name: Install Dart Sass
+  run: sudo snap install dart-sass
+```
+
+If you are using GitHub Pages for the first time with your repository, GitHub provides a [starter workflow] for Hugo that includes Dart Sass. This is the simplest way to get started.
+
+#### GitLab Pages
+
+To install Dart Sass for your builds on GitLab Pages, the `.gitlab-ci.yml` file should look something like this:
+
+```yaml
+variables:
+  HUGO_VERSION: 0.114.0
+  DART_SASS_VERSION: 1.63.5
+  GIT_DEPTH: 0
+  GIT_STRATEGY: clone
+  GIT_SUBMODULE_STRATEGY: recursive
+  TZ: America/Los_Angeles
+image:
+  name: golang:1.20-buster
+pages:
+  script:
+    # Install Dart Sass
+    - curl -LJO https://github.com/sass/dart-sass/releases/download/${DART_SASS_VERSION}/dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz
+    - tar -xf dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz
+    - cp -r dart-sass/* /usr/local/bin
+    - rm -rf dart-sass*
+    # Install Hugo
+    - curl -LJO https://github.com/gohugoio/hugo/releases/download/v${HUGO_VERSION}/hugo_extended_${HUGO_VERSION}_linux-amd64.deb
+    - apt install -y ./hugo_extended_${HUGO_VERSION}_linux-amd64.deb
+    - rm hugo_extended_${HUGO_VERSION}_linux-amd64.deb
+    # Build
+    - hugo --gc --minify
+  artifacts:
+    paths:
+      - public
+  rules:
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
+```
+
+#### Netlify
+
+To install Dart Sass for your builds on Netlify, the `netlify.toml` file should look something like this:
+
+```toml
+[build]
+publish = "public"
+command = """\
+  curl -LJO https://github.com/sass/dart-sass/releases/download/${DART_SASS_VERSION}/dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz && \
+  tar -xf dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz && \
+  mkdir -p /opt/build/repo/node_modules/.bin && \
+  cp -r dart-sass/* /opt/build/repo/node_modules/.bin && \
+  rm -rf dart-sass* && \
+  hugo --gc --minify \
+  """
+
+[build.environment]
+DART_SASS_VERSION = "1.63.5"
+HUGO_VERSION = "0.114.0"
+TZ = "America/Los_Angeles"
+```
+
+### Example
+
+To tranpile with Dart Sass, set `transpiler` to `dartsass` in the options map passed to `resources.ToCSS`. For example:
+
+```go-html-template
+{{ $options := dict "transpiler" "dartsass" "targetPath" "css/style.css" }}
+{{ with resources.Get "sass/main.scss" | toCSS $options | minify | fingerprint }}
+  <link rel="stylesheet" href="{{ .RelPermalink }}" integrity="{{ .Data.Integrity }}" crossorigin="anonymous">
+{{ end }}
+```
+
+### Miscellaneous
+
+If you build Hugo from source and run `mage test -v`, the test will fail if you install Dart Sass as a Snap package. This is due to the Snap package's strict confinement model.
+
+[brew.sh]: https://brew.sh/
+[chocolatey.org]: https://community.chocolatey.org/packages/sass
+[ci/cd]: https://en.wikipedia.org/wiki/CI/CD
+[dart sass]: https://sass-lang.com/dart-sass
+[libsass]: https://sass-lang.com/libsass
+[prebuilt binaries]: https://github.com/sass/dart-sass/releases/latest
+[scoop.sh]: https://scoop.sh/#/apps?q=sass
+[site configuration]: https://gohugo.io/getting-started/configuration/#configure-build
+[snap package]: https://gohugo.io/installation/linux/#snap
+[snapcraft.io]: https://snapcraft.io/dart-sass
+[starter workflow]: https://github.com/actions/starter-workflows/blob/main/pages/hugo.yml

content/en/installation/common/01-editions.md

@@ -2,7 +2,9 @@
 
 Hugo is available in two editions: standard and extended. With the extended edition you can:
 
-- Encode WebP images (you can decode WebP images with both editions)
-- Transpile Sass to CSS using the embedded LibSass transpiler
+- Encode WebP images. You can decode WebP images with either edition.
+- Transpile Sass to CSS using the legacy LibSass transpiler. The extended edition is not required to use the [Dart Sass] transpiler.
 
 We recommend that you install the extended edition.
+
+[dart sass]: /hugo-pipes/transpile-sass-to-css/#dart-sass

content/en/installation/common/02-prerequisites.md

@@ -1,27 +1,37 @@
 ## Prerequisites
 
-Although not required in all cases, Git and Go are often used when working with Hugo.
+Although not required in all cases, [Git], [Go], and [Dart Sass] are commonly used when working with Hugo.
+
 
 Git is required to:
 
-- Use the [Hugo Modules] feature
 - Build Hugo from source
+- Use the [Hugo Modules] feature
 - Install a theme as a Git submodule
 - Access [commit information] from a local Git repository
-- Host your site with services such as [AWS Amplify], [CloudCannon], [Cloudflare Pages], [GitHub Pages], [GitLab Pages], and [Netlify].
+- Host your site with services such as [CloudCannon], [Cloudflare Pages], [GitHub Pages], [GitLab Pages], and [Netlify]
 
 Go is required to:
 
-- Use the Hugo Modules feature
 - Build Hugo from source
+- Use the Hugo Modules feature
+
+Dart Sass is required to transpile modern Sass to CSS.
+
+Please refer to the relevant documentation for installation instructions:
 
-Please refer to the [Git] and [Go] documentation for installation instructions.
+- [Git][git install]
+- [Go][go install]
+- [Dart Sass][dart sass install]
 
-[AWS Amplify]: https://aws.amazon.com/amplify/
-[CloudCannon]: https://cloudcannon.com/
-[Cloudflare Pages]: https://pages.cloudflare.com/
-[Git]: https://git-scm.com/book/en/v2/Getting-Started-Installing-Git
-[GitHub Pages]: https://pages.github.com/
-[GitLab Pages]: https://docs.gitlab.com/ee/user/project/pages/
-[Go]: https://go.dev/doc/install
-[Netlify]: https://www.netlify.com/
+[cloudcannon]: https://cloudcannon.com/
+[cloudflare pages]: https://pages.cloudflare.com/
+[dart sass install]: /hugo-pipes/transpile-sass-to-css/#dart-sass
+[dart sass]: https://sass-lang.com/dart-sass
+[git install]: https://git-scm.com/book/en/v2/getting-started-installing-git
+[git]: https://git-scm.com/
+[github pages]: https://pages.github.com/
+[gitlab pages]: https://docs.gitlab.com/ee/user/project/pages/
+[go install]: https://go.dev/doc/install
+[go]: https://go.dev/
+[netlify]: https://www.netlify.com/