diff --git a/Jenkinsfile b/Jenkinsfile
index ac25f53..9bdbcc7 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -1,11 +1,10 @@
-#!groovy
-def recentLTS = '2.375.2'
+/*
+ See the documentation for more options:
+ https://github.com/jenkins-infra/pipeline-library/
+*/
 buildPlugin(
-  // Container agents start faster and are easier to administer
-  useContainerAgent: true,
+  useContainerAgent: true, // Set to `false` if you need to use Docker for containerized tests
   configurations: [
-    [platform: 'linux',   jdk: '11'],
-    [platform: 'linux',   jdk: '17', jenkins: recentLTS],
-    [platform: 'windows', jdk: '17', jenkins: recentLTS],
-  ]
-)
+    [platform: 'linux', jdk: 21],
+    [platform: 'windows', jdk: 17],
+])
diff --git a/pom.xml b/pom.xml
index 910d6f2..15c5211 100644
--- a/pom.xml
+++ b/pom.xml
@@ -34,7 +34,7 @@
 
   <scm>
     <connection>scm:git:ssh://github.com/${gitHubRepo}.git</connection>
-    <developerConnection>scm:git:ssh://git@github.com/${gitHubRepo}.git</developerConnection>
+    <developerConnection>scm:git:git@github.com:${gitHubRepo}.git</developerConnection>
     <tag>${scmTag}</tag>
     <url>https://github.com/${gitHubRepo}</url>
   </scm>
@@ -42,22 +42,32 @@
   <properties>
     <changelist>999999-SNAPSHOT</changelist>
     <gitHubRepo>jenkinsci/simple-theme-plugin</gitHubRepo>
-    <jenkins.version>2.361.1</jenkins.version>
-    <configuration-as-code.version>1569.vb_72405b_80249</configuration-as-code.version>
+    <jenkins.version>2.421</jenkins.version>
+    <hpi.compatibleSinceVersion>171</hpi.compatibleSinceVersion>
     <spotless.check.skip>false</spotless.check.skip>
   </properties>
 
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>io.jenkins.tools.bom</groupId>
+        <artifactId>bom-2.414.x</artifactId>
+        <version>2357.v1043f8578392</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
   <dependencies>
     <dependency>
       <groupId>io.jenkins</groupId>
       <artifactId>configuration-as-code</artifactId>
-      <version>${configuration-as-code.version}</version>
       <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>io.jenkins.configuration-as-code</groupId>
       <artifactId>test-harness</artifactId>
-      <version>${configuration-as-code.version}</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/src/main/java/org/codefirst/SimpleThemeDecorator.java b/src/main/java/org/codefirst/SimpleThemeDecorator.java
index 944c185..10aac52 100644
--- a/src/main/java/org/codefirst/SimpleThemeDecorator.java
+++ b/src/main/java/org/codefirst/SimpleThemeDecorator.java
@@ -1,11 +1,14 @@
 package org.codefirst;
 
+import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.Extension;
 import hudson.model.PageDecorator;
 import java.util.ArrayList;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
+import jenkins.appearance.AppearanceCategory;
+import jenkins.model.GlobalConfigurationCategory;
 import net.sf.json.JSONObject;
 import org.apache.commons.lang.StringUtils;
 import org.jenkinsci.Symbol;
@@ -20,7 +23,7 @@
 import org.kohsuke.stapler.StaplerRequest;
 
 @Extension
-@Symbol("simple-theme-plugin")
+@Symbol("simpleTheme")
 public class SimpleThemeDecorator extends PageDecorator {
 
     private List<ThemeElement> elements = new ArrayList<>();
@@ -50,6 +53,12 @@ public boolean configure(StaplerRequest req, JSONObject formData) throws FormExc
         return true;
     }
 
+    @NonNull
+    @Override
+    public GlobalConfigurationCategory getCategory() {
+        return GlobalConfigurationCategory.get(AppearanceCategory.class);
+    }
+
     public List<ThemeElement> getElements() {
         return elements;
     }
diff --git a/src/main/resources/org/codefirst/SimpleThemeDecorator/global.groovy b/src/main/resources/org/codefirst/SimpleThemeDecorator/global.groovy
index 6a5db12..ccfa12a 100644
--- a/src/main/resources/org/codefirst/SimpleThemeDecorator/global.groovy
+++ b/src/main/resources/org/codefirst/SimpleThemeDecorator/global.groovy
@@ -4,7 +4,7 @@ import lib.FormTagLib
 
 def f = namespace(FormTagLib)
 
-f.section(title: _("Theme")) {
+f.section(title: _("Customizable theme")) {
     f.entry(title: _("Theme elements")) {
         f.repeatableHeteroProperty(field: "elements", hasHeader: true)
     }
diff --git a/src/test/java/org/jenkinsci/plugins/simpletheme/ConfigurationAsCodeTest.java b/src/test/java/org/jenkinsci/plugins/simpletheme/ConfigurationAsCodeTest.java
index bffe4a7..d2e08f9 100644
--- a/src/test/java/org/jenkinsci/plugins/simpletheme/ConfigurationAsCodeTest.java
+++ b/src/test/java/org/jenkinsci/plugins/simpletheme/ConfigurationAsCodeTest.java
@@ -1,6 +1,5 @@
 package org.jenkinsci.plugins.simpletheme;
 
-import static io.jenkins.plugins.casc.misc.Util.getUnclassifiedRoot;
 import static io.jenkins.plugins.casc.misc.Util.toStringFromYamlFile;
 import static io.jenkins.plugins.casc.misc.Util.toYamlString;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -11,11 +10,17 @@
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertNotNull;
 
+import hudson.ExtensionList;
 import io.jenkins.plugins.casc.ConfigurationContext;
 import io.jenkins.plugins.casc.ConfiguratorRegistry;
+import io.jenkins.plugins.casc.impl.configurators.GlobalConfigurationCategoryConfigurator;
 import io.jenkins.plugins.casc.misc.ConfiguredWithCode;
 import io.jenkins.plugins.casc.misc.JenkinsConfiguredWithCodeRule;
 import io.jenkins.plugins.casc.model.CNode;
+import io.jenkins.plugins.casc.model.Mapping;
+import java.util.Objects;
+import jenkins.appearance.AppearanceCategory;
+import jenkins.model.GlobalConfigurationCategory;
 import org.codefirst.SimpleThemeDecorator;
 import org.junit.ClassRule;
 import org.junit.Test;
@@ -44,7 +49,7 @@ public void testConfig() {
     @Test
     public void testExport() throws Exception {
         ConfigurationContext context = new ConfigurationContext(ConfiguratorRegistry.get());
-        CNode yourAttribute = getUnclassifiedRoot(context).get("simple-theme-plugin");
+        CNode yourAttribute = getAppearanceRoot(context).get("simpleTheme");
 
         String exported = toYamlString(yourAttribute);
 
@@ -52,4 +57,12 @@ public void testExport() throws Exception {
 
         assertThat(exported, is(expected));
     }
+
+    private static Mapping getAppearanceRoot(ConfigurationContext context) throws Exception {
+        GlobalConfigurationCategory category =
+                ExtensionList.lookup(AppearanceCategory.class).get(0);
+        GlobalConfigurationCategoryConfigurator configurator = new GlobalConfigurationCategoryConfigurator(category);
+        return Objects.requireNonNull(configurator.describe(configurator.getTargetComponent(context), context))
+                .asMapping();
+    }
 }
diff --git a/src/test/java/org/jenkinsci/plugins/simpletheme/SimpleThemeConfigurationTest.java b/src/test/java/org/jenkinsci/plugins/simpletheme/SimpleThemeConfigurationTest.java
index 8ea3256..5702f33 100644
--- a/src/test/java/org/jenkinsci/plugins/simpletheme/SimpleThemeConfigurationTest.java
+++ b/src/test/java/org/jenkinsci/plugins/simpletheme/SimpleThemeConfigurationTest.java
@@ -27,7 +27,7 @@ public void testConfigRoundTrip() throws Exception {
         SimpleThemeDecorator decorator = j.jenkins.getDescriptorByType(SimpleThemeDecorator.class);
         fill(decorator);
 
-        j.configRoundtrip();
+        configRoundTrip();
 
         decorator = j.jenkins.getDescriptorByType(SimpleThemeDecorator.class);
 
@@ -35,12 +35,16 @@ public void testConfigRoundTrip() throws Exception {
         assertThat(decorator.getElements(), hasSize(4));
     }
 
+    private void configRoundTrip() throws Exception {
+        j.submit(j.createWebClient().goTo("manage/appearance").getFormByName("config"));
+    }
+
     @Test
     public void testConfigCreatesHtml() throws Exception {
         SimpleThemeDecorator decorator = j.jenkins.getDescriptorByType(SimpleThemeDecorator.class);
         fill(decorator);
 
-        HtmlPage configPage = j.createWebClient().goTo("configure");
+        HtmlPage configPage = j.createWebClient().goTo("manage/appearance");
         HtmlForm form = configPage.getFormByName("config");
 
         urlThemeInput(form, CssUrlThemeElement.class).setValue("SOMECSSFILE.css");
diff --git a/src/test/resources/org/jenkinsci/plugins/simpletheme/ConfigurationAsCode.yml b/src/test/resources/org/jenkinsci/plugins/simpletheme/ConfigurationAsCode.yml
index db2d63c..161a387 100644
--- a/src/test/resources/org/jenkinsci/plugins/simpletheme/ConfigurationAsCode.yml
+++ b/src/test/resources/org/jenkinsci/plugins/simpletheme/ConfigurationAsCode.yml
@@ -1,6 +1,6 @@
 ---
-unclassified:
-  simple-theme-plugin:
+appearance:
+  simpleTheme:
     elements:
       - cssUrl:
           url: "https://example.bogus/test.css"