Correct css.sass warnings (#754)

<!-- markdownlint-disable MD041 -->
#### What this PR does / why we need it
Add version pinning for dart-sass, so that workflow and netlify preview
are in sync.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Chores**
* Updated site publication workflow to pin a specific Dart Sass version
(bumped to 1.98.0) and switch to a user-local installation approach,
ensuring consistent, reproducible builds and removing reliance on system
package installs. Added creation of a user-local executable directory
and explicit version env settings for more reliable deployments.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Gerald Morrison (SAP) <gerald.morrison@sap.com>
Co-authored-by: Gerald Morrison (SAP) <gerald.morrison@sap.com>
Co-authored-by: Matthias Bruns <git@matthiasbruns.com>

Author: 3 people

.github/workflows/publish-site.yaml

@@ -15,6 +15,9 @@ jobs:
     name: Publish Site
     runs-on: ubuntu-latest
 
+    env:
+      DART_SASS_VERSION: 1.98.0
+
     permissions:
       contents: write
       id-token: write
@@ -44,8 +47,17 @@ jobs:
           hugo-version: '0.155.0'
           extended: true
 
+      # For the installation of dart sass follow https://gohugo.io/functions/css/sass/#dart-sass and
+      # https://gohugo.io/host-and-deploy/host-on-github-pages/
+      - name: Create directory for user-specific executable files
+        run: mkdir -p "${HOME}/.local"
+
       - name: Install Dart Sass
-        run: sudo snap install dart-sass
+        run: |
+          curl -sLJO "https://github.com/sass/dart-sass/releases/download/${DART_SASS_VERSION}/dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz"
+          tar -C "${HOME}/.local" -xf "dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz"
+          rm "dart-sass-${DART_SASS_VERSION}-linux-x64.tar.gz"
+          echo "${HOME}/.local/dart-sass" >> "${GITHUB_PATH}"
 
       - name: Install deps and Build
         run: |

netlify.toml

@@ -1,5 +1,7 @@
 [build.environment]
-  DART_SASS_VERSION = "1.97.3"
+  # For the installation of dart sass follow https://gohugo.io/functions/css/sass/#dart-sass and
+  # https://gohugo.io/host-and-deploy/host-on-github-pages/
+  DART_SASS_VERSION = "1.98.0"
   NODE_VERSION = "25.6.1"
   NPM_VERSION = "11.9.0"