diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..3729c2c
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,26 @@
+name: CI
+on:
+  push:
+    branches:
+      - '*'
+  pull_request:
+    branches:
+      - '*'
+  merge_group:
+    types: [ checks_requested ]
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.6
+          # runs 'bundle install' and caches installed gems automatically
+          bundler-cache: true
+      - name: jekyll build
+        run: bundle exec jekyll build
+      - name: htmlproofer
+        run: bundle exec htmlproofer _site/ --disable-external=true
diff --git a/_includes/_head.html b/_includes/_head.html
index fcaffb9..0cd863c 100644
--- a/_includes/_head.html
+++ b/_includes/_head.html
@@ -43,7 +43,7 @@
 <!-- Modernizr -->
 <script src="{{ site.url }}/assets/js/vendor/modernizr-2.7.1.custom.min.js"></script>
 
-<link href='//fonts.googleapis.com/css?family=PT+Sans+Narrow:400,700%7CPT+Serif:400,700,400italic' rel='stylesheet' type='text/css'>
+<link href='https://fonts.googleapis.com/css?family=PT+Sans+Narrow:400,700%7CPT+Serif:400,700,400italic' rel='stylesheet' type='text/css'>
 
 <!-- Icons -->
 <link rel="shortcut icon" href="/images/favicon.ico" type="image/x-icon"/>
diff --git a/downloads/index.md b/downloads/index.md
index df5a717..43c56f9 100644
--- a/downloads/index.md
+++ b/downloads/index.md
@@ -30,5 +30,5 @@ image:
 
 * Java implementation
 
-    [http://undertow.io/downloads.html](http://undertow.io/downloads.html)
+    [https://undertow.io/downloads.html](https://undertow.io/downloads.html)
 
diff --git a/index.md b/index.md
index fbb4efc..f525d3f 100644
--- a/index.md
+++ b/index.md
@@ -40,7 +40,7 @@ implementation, whereas the C implementation is now in a separate repository as
 mod_proxy_cluster.
 
 A pure-Java load balancer implementation is available as part of
-[Undertow](http://undertow.io/). Container integration modules are available
+[Undertow](https://undertow.io/). Container integration modules are available
 for [WildFly](https://wildfly.org) (formerly known as JBoss AS), JBoss EAP and
 Apache [Tomcat](https://tomcat.apache.org).
 
diff --git a/script/cibuild b/script/cibuild
deleted file mode 100644
index fed08cb..0000000
--- a/script/cibuild
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/usr/bin/env bash
-set -e # halt script on error
-
-bundle exec jekyll build
-bundle exec htmlproofer ./_site --internal-domains=modcluster.io --check-html