Use Dart Sass

libsass (the default) is no longer supported. jekyll-sass-converter has
yet to do a release that contains the Dart Sass implementation, so we
import from the main branch directly. See
jekyll/jekyll-sass-converter#116 (comment)
for more details.

Gemfile

@@ -4,4 +4,6 @@ gem "nokogiri"
 
 # If you have any plugins, put them here!
 group :jekyll_plugins do
+  gem "jekyll-sass-converter", github: 'jekyll/jekyll-sass-converter'
+  gem "sass-embedded"
 end

Gemfile.lock

@@ -1,3 +1,10 @@
+GIT
+  remote: https://github.com/jekyll/jekyll-sass-converter.git
+  revision: 5d130e8791fc45f60ca7b41c1926b1ee8bf1e279
+  specs:
+    jekyll-sass-converter (2.1.0)
+      sassc (> 2.0.1, < 3.0)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -11,6 +18,7 @@ GEM
     eventmachine (1.2.7)
     ffi (1.15.4)
     forwardable-extended (2.6.0)
+    google-protobuf (3.19.3)
     http_parser.rb (0.8.0)
     i18n (1.8.11)
       concurrent-ruby (~> 1.0)
@@ -29,8 +37,6 @@ GEM
       rouge (~> 3.0)
       safe_yaml (~> 1.0)
       terminal-table (~> 2.0)
-    jekyll-sass-converter (2.1.0)
-      sassc (> 2.0.1, < 3.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
     kramdown (2.3.1)
@@ -58,6 +64,8 @@ GEM
     rexml (3.2.5)
     rouge (3.27.0)
     safe_yaml (1.0.5)
+    sass-embedded (0.11.0)
+      google-protobuf (~> 3.19.0)
     sassc (2.4.0)
       ffi (~> 1.9)
     terminal-table (2.0.0)
@@ -70,7 +78,9 @@ PLATFORMS
 
 DEPENDENCIES
   jekyll (~> 4.2.1)
+  jekyll-sass-converter!
   nokogiri
+  sass-embedded
 
 BUNDLED WITH
    2.3.4

_config.yml

@@ -26,6 +26,8 @@ collections:
 # Site settings
 
 # Build settings
+sass:
+  implementation: sass-embedded
 # plugins:
 
 # Exclude from processing.