diff --git a/FUNDING.yml b/.github/FUNDING.yml
similarity index 100%
rename from FUNDING.yml
rename to .github/FUNDING.yml
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
new file mode 100644
index 0000000..82795b2
--- /dev/null
+++ b/.github/workflows/tests.yml
@@ -0,0 +1,133 @@
+name: Tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+env:
+  PACKAGE_FOLDER: Shel.CriticalCSS
+
+jobs:
+  codestyle:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 8.2
+
+      - name: Add additional dependencies
+        run: |
+          composer require --no-update --no-interaction neos/contentgraph-doctrinedbaladapter:"~9.0.0"
+
+      - name: Cache dependencies
+        uses: actions/cache@v3
+        with:
+          path: ~/.composer/cache
+          key: dependencies-composer-${{ hashFiles('composer.json') }}
+
+      - name: Install dependencies
+        uses: php-actions/composer@v6
+        with:
+          php_version: 8.2
+          version: 2
+
+      - name: PHPStan
+        uses: php-actions/phpstan@v3
+        with:
+          php_version: 8.2
+          version: 2.1.17
+          command: analyse
+          path: 'Classes/'
+
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php-versions:
+          - '8.2'
+        neosVersion:
+          - '9.0'
+
+    services:
+      mariadb:
+        # see https://mariadb.com/kb/en/mariadb-server-release-dates/
+        # this should be a current release, e.g. the LTS version
+        image: mariadb:10.8
+        env:
+          MYSQL_USER: neos
+          MYSQL_PASSWORD: neos
+          MYSQL_DATABASE: neos_functional_testing
+          MYSQL_ROOT_PASSWORD: neos
+        ports:
+          - "3306:3306"
+        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
+
+    name: 'Shel.CriticalCSS with Neos ${{ matrix.neosVersion }} test'
+
+    env:
+      NEOS_TARGET_VERSION: ${{matrix.neosVersion}}
+      FLOW_CONTEXT: Testing
+      FLOW_FOLDER: ../neos-base-distribution
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set package branch name
+        run: echo "PACKAGE_TARGET_VERSION=${GITHUB_BASE_REF:-${GITHUB_REF#refs/heads/}}" >> $GITHUB_ENV
+        working-directory: .
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+          extensions: mbstring, xml, json, zlib, iconv, intl, pdo_sqlite, mysql
+          tools: composer:v2
+
+      - name: Cache dependencies
+        uses: actions/cache@v3
+        with:
+          path: ~/.composer/cache
+          key: dependencies-composer-${{ hashFiles('composer.json') }}
+
+      - name: Prepare Flow distribution
+        run: |
+          git clone https://github.com/neos/neos-base-distribution.git -b ${NEOS_TARGET_VERSION} ${FLOW_FOLDER}
+          cd ${FLOW_FOLDER}
+
+          git -C ../${{ env.PACKAGE_FOLDER }} checkout -b build
+          composer config repositories.package '{ "type": "path", "url": "../${{ env.PACKAGE_FOLDER }}", "options": { "symlink": false } }'
+          composer require --no-update --no-interaction shel/critical-css:"dev-build as dev-${PACKAGE_TARGET_VERSION}"
+          composer require --no-update --no-interaction neos/contentgraph-doctrinedbaladapter:"~9.0.0"
+
+      - name: Composer Install
+        run: |
+          cd ${FLOW_FOLDER}
+          composer update --no-interaction --no-progress
+
+      - name: Setup Flow configuration
+        run: |
+          cd ${FLOW_FOLDER}
+          rm -f Configuration/Testing/Settings.yaml
+          cat <<EOF >> Configuration/Testing/Settings.yaml
+          Neos:
+            Flow:
+              persistence:
+                backendOptions:
+                  host: '127.0.0.1'
+                  driver: pdo_mysql
+                  user: 'neos'
+                  password: 'neos'
+                  dbname: 'neos_functional_testing'
+          EOF
+
+      - name: Run Functional tests
+        run: |
+          cd ${FLOW_FOLDER}
+          bin/phpunit --colors -c Build/BuildEssentials/PhpUnit/FunctionalTests.xml Packages/Plugins/Shel.CriticalCSS/Tests/Functional/
diff --git a/.styleci.yml b/.styleci.yml
deleted file mode 100644
index 14c4d58..0000000
--- a/.styleci.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-preset: psr2
-
-finder:
-  path:
-    - "Classes"
-    - "Tests"
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 4703c80..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,23 +0,0 @@
-language: php
-sudo: false
-git:
-    depth: 5
-    submodules: false
-matrix:
-    include:
-        - php: 7.4
-
-before_install:
-    - export FLOW_TARGET_VERSION=7.0
-    - cd ..
-    - git clone https://github.com/neos/flow-base-distribution.git -b ${FLOW_TARGET_VERSION}
-    - cd flow-base-distribution
-    - composer require --no-update --no-interaction shel/critical-css
-install:
-    - composer install --no-interaction
-    - cd ..
-    - rm -rf flow-base-distribution/Packages/Plugins/Shel.CriticalCSS
-    - mv Shel.CriticalCSS flow-base-distribution/Packages/Plugins/Shel.CriticalCSS
-    - cd flow-base-distribution
-script:
-    - bin/phpunit --colors -c Build/BuildEssentials/PhpUnit/FunctionalTests.xml Packages/Plugins/Shel.CriticalCSS/Tests/Functional/
diff --git a/Classes/Command/StylesCommandController.php b/Classes/Command/StylesCommandController.php
index b1fe6ee..ae7629b 100644
--- a/Classes/Command/StylesCommandController.php
+++ b/Classes/Command/StylesCommandController.php
@@ -11,33 +11,18 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Cli\CommandController;
 use Neos\Flow\Mvc\ActionRequest;
-use Neos\Flow\Mvc\ActionResponse;
-use Neos\Flow\Mvc\Controller\Arguments;
-use Neos\Flow\Mvc\Controller\ControllerContext;
-use Neos\Flow\Mvc\Routing\UriBuilder;
 use Neos\Flow\Security\Exception as SecurityException;
 use Neos\Neos\Domain\Repository\SiteRepository;
 use Shel\CriticalCSS\Fusion\FusionView;
-use Shel\CriticalCSS\Service\FusionService;
 
 /**
  * The User Command Controller
- *
- * @Flow\Scope("singleton")
  */
+#[Flow\Scope('singleton')]
 class StylesCommandController extends CommandController
 {
-    /**
-     * @Flow\Inject
-     * @var SiteRepository
-     */
-    protected $siteRepository;
-
-    /**
-     * @Flow\Inject
-     * @var FusionService
-     */
-    protected $fusionService;
+    #[Flow\Inject]
+    protected SiteRepository $siteRepository;
 
     /**
      * This command returns all styles for a given site node and prototype name.
@@ -56,7 +41,7 @@ public function exportCommand(string $siteNodeName, string $basePrototypeName =
         }
 
         $fusionView = new FusionView();
-        $fusionView->setControllerContext($this->createSimpleControllerContext());
+        $fusionView->assign('request', $this->createSimpleControllerRequest());
         $fusionView->setFusionPath('shelCriticalStyles');
         $fusionView->setPackageKey($site->getSiteResourcesPackageKey());
         $fusionView->assign('site', $site->getNodeName());
@@ -65,17 +50,11 @@ public function exportCommand(string $siteNodeName, string $basePrototypeName =
     }
 
     /**
-     * Create a simple controller context which can be used to instantiate a Fusion runtime etc.
+     * Create a simple controller context which can be used to instantiate a Fusion runtime, etc.
      */
-    protected function createSimpleControllerContext(): ControllerContext
+    protected function createSimpleControllerRequest(): ActionRequest
     {
         $httpRequest = new ServerRequest('POST', 'http://localhost');
-        $request = ActionRequest::fromHttpRequest($httpRequest);
-        $response = new ActionResponse();
-        $arguments = new Arguments([]);
-        $uriBuilder = new UriBuilder();
-        $uriBuilder->setRequest($request);
-
-        return new ControllerContext($request, $response, $arguments, $uriBuilder);
+        return ActionRequest::fromHttpRequest($httpRequest);
     }
 }
diff --git a/Classes/Fusion/FusionView.php b/Classes/Fusion/FusionView.php
index 5322627..4b549cb 100644
--- a/Classes/Fusion/FusionView.php
+++ b/Classes/Fusion/FusionView.php
@@ -10,7 +10,8 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Mvc\Exception;
 use Neos\Flow\Security\Exception as SecurityException;
-use Neos\FluidAdaptor\View\TemplateView;
+use Neos\Fusion\Core\FusionConfiguration;
+use Neos\Fusion\Core\FusionGlobals;
 use Neos\Fusion\View\FusionView as BaseFusionView;
 use Neos\Fusion\Core\Runtime as FusionRuntime;
 use Shel\CriticalCSS\Service\FusionService;
@@ -20,30 +21,20 @@
  */
 class FusionView extends BaseFusionView
 {
-    protected $styleRenderPath = 'shelCriticalStyles';
+    protected string $styleRenderPath = 'shelCriticalStyles';
 
-    /**
-     * @Flow\Inject
-     * @var FusionService
-     */
-    protected $fusionService;
-
-    /**
-     * @Flow\Inject
-     * @var TemplateView
-     */
-    protected $fallbackView;
+    #[Flow\Inject]
+    protected FusionService $fusionService;
 
     /**
      * @inheritDoc
+     * @throws Exception
      */
     protected function loadFusion(): void
     {
-        $fusionAst = [];
-        try {
-            $fusionAst = $this->fusionService->getMergedFusionObjectTreeForSitePackage($this->getOption('packageKey'));
-        } catch (Exception $e) {
-        }
+        $fusionAst = $this->fusionService->getFusionConfigurationForSitePackage(
+            $this->getOption('packageKey')
+        );
         $this->parsedFusion = $fusionAst;
     }
 
@@ -51,24 +42,31 @@ protected function loadFusion(): void
      * Iterates through the Fusion AST and renders all instantiated
      * objects of the given prototype and returns the concatenated results as string.
      *
-     * @param string $stylePrototypeName
-     * @return string
      * @throws SecurityException
      */
     public function renderStyles(string $stylePrototypeName): string
     {
+        /** @noinspection PhpConditionAlreadyCheckedInspection */
+        /** @phpstan-ignore booleanNot.alwaysFalse */
         if (!$this->parsedFusion) {
-            $this->loadFusion();
+            try {
+                $this->loadFusion();
+            } catch (Exception) {
+                return '';
+            }
+        }
+        $fusionAst = $this->parsedFusion->toArray();
+        $prototypes = $fusionAst['__prototypes'] ?? [];
+
+        if (!$prototypes) {
+            return '';
         }
-        $fusionAst = $this->parsedFusion;
-        $prototypes = $fusionAst['__prototypes'];
 
         $arrayIterator = new \RecursiveIteratorIterator(new \RecursiveArrayIterator($fusionAst));
         $outputArray = [];
         /** @noinspection PhpUnusedLocalVariableInspection */
         foreach ($arrayIterator as $sub) {
-            $subArray = $arrayIterator->getSubIterator();
-            /** @noinspection PhpParamsInspection */
+            $subArray = iterator_to_array($arrayIterator->getSubIterator());
             if (!array_key_exists('__objectType', $subArray)) {
                 continue;
             }
@@ -77,7 +75,7 @@ public function renderStyles(string $stylePrototypeName): string
                 ($prototypeName
                     && array_key_exists($prototypeName, $prototypes)
                     && array_key_exists('__prototypeChain', $prototypes[$prototypeName])
-                    && in_array($stylePrototypeName, $prototypes[$prototypeName]['__prototypeChain']))) {
+                    && in_array($stylePrototypeName, $prototypes[$prototypeName]['__prototypeChain'], true))) {
                 $props = iterator_to_array($subArray);
                 $props['__meta']['stylesOnly'] = true;
                 $outputArray[] = $props;
@@ -89,7 +87,10 @@ public function renderStyles(string $stylePrototypeName): string
         // Render each found instantiated prototype
         foreach ($outputArray as $props) {
             $fusionAst[$this->styleRenderPath] = $props;
-            $fusionRuntime = new FusionRuntime($fusionAst, $this->controllerContext);
+            $fusionGlobals = FusionGlobals::fromArray(array_filter([
+                'request' => $this->assignedActionRequest,
+            ]));
+            $fusionRuntime = new FusionRuntime(FusionConfiguration::fromArray($fusionAst), $fusionGlobals);
             $fusionRuntime->pushContextArray($this->variables);
             $output .= $fusionRuntime->render($this->styleRenderPath);
             $fusionRuntime->popContext();
diff --git a/Classes/FusionObjects/LoadStylesImplementation.php b/Classes/FusionObjects/LoadStylesImplementation.php
index 0bf856c..b655643 100644
--- a/Classes/FusionObjects/LoadStylesImplementation.php
+++ b/Classes/FusionObjects/LoadStylesImplementation.php
@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 namespace Shel\CriticalCSS\FusionObjects;
@@ -17,8 +18,6 @@ class LoadStylesImplementation extends AbstractFusionObject
 {
     /**
      * HTML content that should be processed (optional)
-     *
-     * @return string|null
      */
     protected function getContent(): ?string
     {
@@ -27,22 +26,17 @@ protected function getContent(): ?string
 
     /**
      * Path to a CSS resource
-     *
-     * @return string
      */
     protected function getPath(): string
     {
         return $this->fusionValue('path');
     }
 
-    /**
-     * @return string
-     */
     public function evaluate(): string
     {
         try {
             $styles = $this->loadResourceContent($this->getPath());
-        } catch (InvalidVariableException $e) {
+        } catch (InvalidVariableException) {
             throw new \InvalidArgumentException('Resource ' . $this->getPath() . ' cannot be loaded!', 1573314641);
         }
 
@@ -51,8 +45,6 @@ public function evaluate(): string
 
     /**
      * Loads the content of a resource and returns it as string
-     *
-     * @return string Content of the resource
      * @throws InvalidVariableException
      */
     public function loadResourceContent(?string $path): string
@@ -60,7 +52,6 @@ public function loadResourceContent(?string $path): string
         if ($path === null) {
             throw new InvalidVariableException('You have to define a path.', 1573317165);
         }
-
-        return file_get_contents($path);
+        return file_get_contents($path) ?: '';
     }
 }
diff --git a/Classes/FusionObjects/StyleCollectorImplementation.php b/Classes/FusionObjects/StyleCollectorImplementation.php
index 8da6652..02564f0 100644
--- a/Classes/FusionObjects/StyleCollectorImplementation.php
+++ b/Classes/FusionObjects/StyleCollectorImplementation.php
@@ -11,7 +11,7 @@
 
 /**
  * Collects all style tags defined with the `Shel.CriticalCSS:Styles` object
- * and puts them in the html head or at the start of the object the collector is applied to.
+ * and puts them in the HTML head or at the start of the object the collector is applied to.
  */
 class StyleCollectorImplementation extends AbstractFusionObject
 {
@@ -22,21 +22,30 @@ public function evaluate()
     {
         $content = $this->fusionValue('content');
 
-        preg_match_all('/<style data-inline>(.*?)<\/style>/', $content, $matches);
-
-        if (!$matches) {
+        $occurrences = preg_match_all('/<style data-inline>(.*?)<\/style>/', $content, $matches);
+        if (!$occurrences) {
             return $content;
         }
 
         $styles = array_unique($matches[1]);
-        $content = preg_replace('/<style data-inline>.*?<\/style>/', '', $content);
+        /** @var string $modifiedContent */
+        $modifiedContent = preg_replace('/[ \t]*<style data-inline>.*?<\/style>\n?/s', '', $content);
+
+        if (!$modifiedContent) {
+            return $content;
+        }
 
         $styleTag = '<style>' . implode('', $styles) . '</style>';
 
-        if (strpos($content, '</head>') !== false) {
-            return str_replace('</head>', $styleTag . '</head>', $content);
+        if (str_contains($modifiedContent, '</head>')) {
+            /** @var string $modifiedContent */
+            $modifiedContent = str_replace('</head>', $styleTag . '</head>', $modifiedContent);
+            if ($modifiedContent) {
+                return $modifiedContent;
+            }
+            return $content;
         }
 
-        return $styleTag . $content;
+        return $styleTag . $modifiedContent;
     }
 }
diff --git a/Classes/FusionObjects/StylesImplementation.php b/Classes/FusionObjects/StylesImplementation.php
index 83a4d85..60af901 100644
--- a/Classes/FusionObjects/StylesImplementation.php
+++ b/Classes/FusionObjects/StylesImplementation.php
@@ -14,36 +14,28 @@
 use Shel\CriticalCSS\Service\StylesService;
 
 /**
- * Adds all attributes as css styles into a style tag with a css class and adds the class to the tag
+ * Adds all attributes as CSS styles into a style tag with a CSS class and adds the class to the tag
  */
 class StylesImplementation extends DataStructureImplementation
 {
 
-    /**
-     * @Flow\Inject
-     * @var HtmlAugmenter
-     */
-    protected $htmlAugmenter;
+    #[Flow\Inject]
+    protected HtmlAugmenter $htmlAugmenter;
 
-    /**
-     * @Flow\Inject
-     * @var StylesService
-     */
-    protected $stylesService;
+    #[Flow\Inject]
+    protected StylesService $stylesService;
 
     /**
      * Properties that are ignored
      *
-     * @var array
+     * @var string[]
      */
     protected $ignoreProperties = ['__meta'];
 
     /**
-     * The content that will be applied the generated css class or
+     * The content that will be applied the generated CSS class or
      * if it's multiple elements they will be wrapped with a new
      * tag and the generated class. See `fallbackTagName`.
-     *
-     * @return string
      */
     protected function getContent(): string
     {
@@ -54,8 +46,6 @@ protected function getContent(): string
      * The tag that will be used when content contains multiple tags
      * and needs to be wrapped for a class to be applied.
      * This behaves the same as with the HTML Augmenter.
-     *
-     * @return string
      */
     protected function getFallbackTagName(): string
     {
@@ -63,11 +53,9 @@ protected function getFallbackTagName(): string
     }
 
     /**
-     * When this is set a selector is used instead of the generated class.
-     *
-     * @return bool|string
+     * When this is set, a selector is used instead of the generated class.
      */
-    protected function getSelector()
+    protected function getSelector(): bool|string
     {
         return $this->fusionValue('__meta/selector') ?? false;
     }
@@ -86,13 +74,13 @@ protected function getClassPrefix(): string
     }
 
     /**
-     * @return string
      * @throws FusionException
+     * @phpstan-ignore method.childReturnType
      */
     public function evaluate(): string
     {
         $content = $this->getContent();
-        $sortedChildFusionKeys = $this->sortNestedFusionKeys();
+        $sortedChildFusionKeys = $this->preparePropertyKeys($this->properties, $this->ignoreProperties);
         $selector = $this->getSelector();
         $classPrefix = $this->getClassPrefix();
 
@@ -100,7 +88,7 @@ public function evaluate(): string
         foreach ($sortedChildFusionKeys as $key) {
             $value = $this->fusionValue($key);
 
-            // When using simple nesting with `{` instead of using Neos.Fusion:DataStructure
+            // When using simple nesting with `{` instead of using Neos.Fusion:DataStructure,
             // we have to retrieve the value from the properties as the value is null.
             if ($value === null && array_key_exists($key, $this->properties)) {
                 $value = $this->properties[$key];
@@ -112,7 +100,7 @@ public function evaluate(): string
             $styleProperties[$key] = $value;
         }
 
-        $path = [$selector !== false ? $selector : '.' . $classPrefix . '#{$hash}'];
+        $path = [$selector !== false ? (string)$selector : '.' . $classPrefix . '#{$hash}'];
         $stylesHash = $this->stylesService->getHashForStyles($styleProperties, $path);
         $styles = $this->stylesService->renderStyles($styleProperties, $path);
         $styles = str_replace('#{$hash}', $stylesHash, $styles);
@@ -139,7 +127,7 @@ public function evaluate(): string
 
     /**
      * @param string $path
-     * @param array $props
+     * @param array<string, mixed> $props
      */
     protected function evaluateNestedProps(string $path, array &$props): void
     {
diff --git a/Classes/Http/StyleMiddleware.php b/Classes/Http/StyleMiddleware.php
index e7504b4..57cebd0 100644
--- a/Classes/Http/StyleMiddleware.php
+++ b/Classes/Http/StyleMiddleware.php
@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 namespace Shel\CriticalCSS\Http;
@@ -15,22 +16,14 @@
 use Psr\Http\Server\RequestHandlerInterface;
 
 /**
- * The HTTP component to collect all inline styles and merge them into the html head
+ * The HTTP component to collect all inline styles and merge them into the HTML head
  */
 class StyleMiddleware implements MiddlewareInterface
 {
 
-    /**
-     * @var boolean
-     * @Flow\InjectConfiguration(path="mergeStyles.enabled")
-     */
-    protected $enabled;
-
-    /**
-     * @param ServerRequestInterface $request
-     * @param RequestHandlerInterface $handler
-     * @return ResponseInterface
-     */
+    #[Flow\InjectConfiguration('mergeStyles.enabled')]
+    protected bool $enabled = false;
+
     public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
     {
         $response = $handler->handle($request);
@@ -39,17 +32,16 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
             return $response;
         }
 
-        if (strpos($request->getUri()->getPath(), '/neos/') === 0) {
+        if (str_starts_with($request->getUri()->getPath(), '/neos/')) {
             return $response;
         }
 
-        $content = $response->getBody()->getContents();
+        $renderedContent = $response->getBody()->getContents();
         $response->getBody()->rewind();
 
         // Retrieve all inline style tags
-        preg_match_all('/<style data-inline>(.*?)<\/style>/', $content, $matches);
-
-        if (!$matches) {
+        $foundOccurrences = preg_match_all('/<style data-inline>(.*?)<\/style>/', $renderedContent, $matches);
+        if (!$foundOccurrences) {
             return $response;
         }
 
@@ -61,11 +53,15 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
         }
 
         // Remove inline style tags from content
-        $content = preg_replace('/<style data-inline>.*?<\/style>/', '', $content);
-
-        // Add merged styles into one new style tag to head
-        $styleTag = '<style data-merged>' . implode('', $styles) . '</style>';
-        $content = str_replace('</head>', $styleTag . '</head>', $content);
+        $content = preg_replace('/<style data-inline>.*?<\/style>/s', '', $renderedContent);
+
+        if ($content) {
+            // Add merged styles into one new style tag to head
+            $styleTag = '<style data-merged>' . implode('', $styles) . '</style>';
+            $content = str_replace('</head>', $styleTag . '</head>', $content);
+        } else {
+            $content = $renderedContent;
+        }
 
         return $response->withBody(ContentStream::fromContents($content));
     }
diff --git a/Classes/Service/FusionService.php b/Classes/Service/FusionService.php
index 2a1f018..dbdb091 100644
--- a/Classes/Service/FusionService.php
+++ b/Classes/Service/FusionService.php
@@ -8,8 +8,8 @@
  */
 
 use Neos\Flow\Annotations as Flow;
-use Neos\Fusion\Exception as FusionException;
-use Neos\Neos\Domain\Exception as DomainException;
+use Neos\Fusion\Core\FusionConfiguration;
+use Neos\Neos\Domain\Repository\SiteRepository;
 use Neos\Neos\Domain\Service\FusionService as NeosFusionService;
 
 /**
@@ -17,30 +17,17 @@
 class FusionService extends NeosFusionService
 {
 
-    /**
-     * @Flow\InjectConfiguration(path="fusion.autoInclude", package="Neos.Neos")
-     * @var array
-     */
-    protected $autoIncludeConfiguration = [];
+    #[Flow\Inject]
+    protected SiteRepository $siteRepository;
 
     /**
      * Returns a merged fusion object tree in the context of the given site-package
-     *
-     * @param string $siteResourcesPackageKey
-     * @return array The merged object tree as of the given node
-     * @throws DomainException
-     * @throws FusionException
      */
-    public function getMergedFusionObjectTreeForSitePackage(string $siteResourcesPackageKey): array
+    public function getFusionConfigurationForSitePackage(string $siteResourcesPackageKey): FusionConfiguration
     {
-        $siteRootFusionPathAndFilename = sprintf($this->siteRootFusionPattern, $siteResourcesPackageKey);
-
-        $mergedFusionCode = $this->generateNodeTypeDefinitions();
-        $mergedFusionCode .= $this->getFusionIncludes($this->prepareAutoIncludeFusion());
-        $mergedFusionCode .= $this->getFusionIncludes($this->prependFusionIncludes);
-        $mergedFusionCode .= $this->readExternalFusionFile($siteRootFusionPathAndFilename);
-        $mergedFusionCode .= $this->getFusionIncludes($this->appendFusionIncludes);
+        /** @noinspection PhpUndefinedMethodInspection */
+        $site = $this->siteRepository->findOneBySiteResourcesPackageKey($siteResourcesPackageKey);
 
-        return $this->fusionParser->parse($mergedFusionCode, $siteRootFusionPathAndFilename);
+        return $this->createFusionConfigurationFromSite($site);
     }
 }
diff --git a/Classes/Service/StylesService.php b/Classes/Service/StylesService.php
index 3532cf7..c1fb15c 100644
--- a/Classes/Service/StylesService.php
+++ b/Classes/Service/StylesService.php
@@ -11,20 +11,18 @@
 
 /**
  * The User Command Controller
- *
- * @Flow\Scope("singleton")
  */
+#[Flow\Scope('singleton')]
 class StylesService
 {
     /**
-     * @var array
+     * @var array<string, string>
      */
-    protected $stylesCache = [];
+    protected array $stylesCache = [];
 
     /**
-     * @param array $styleProperties
-     * @param array $path
-     * @return string
+     * @param array<string, string> $styleProperties
+     * @param string[] $path
      */
     public function getHashForStyles(array $styleProperties, array $path = []): string
     {
@@ -32,9 +30,8 @@ public function getHashForStyles(array $styleProperties, array $path = []): stri
     }
 
     /**
-     * @param array $styleProperties
-     * @param array $path
-     * @return string
+     * @param array<string, string> $styleProperties
+     * @param string[] $path
      */
     public function renderStyles(array $styleProperties, array $path = []): string
     {
@@ -50,15 +47,14 @@ public function renderStyles(array $styleProperties, array $path = []): string
     }
 
     /**
-     * @param array $properties
-     * @param array $path
-     * @return string
+     * @param array<string, mixed> $properties
+     * @param string[] $path
      */
     protected function renderProperties(array $properties, array $path = []): string
     {
         // Construct full CSS selector
         $pathName = implode(' ', array_map(static function ($part) {
-            return strpos($part, '@') === 0 ? $part . '{' : $part;
+            return str_starts_with($part, '@') ? $part . '{' : $part;
         }, $path));
         $pathName = str_replace('{ ', '{', $pathName);
 
@@ -68,10 +64,10 @@ protected function renderProperties(array $properties, array $path = []): string
             if (is_iterable($styleValue)) {
                 $childPath = array_merge($path, [$styleName]);
                 // Check for @media or @supports queries and reorder the selector
-                if (strpos($styleName, '@') === 0) {
-                    usort($childPath, 'self::compareSelectorParts');
+                if (str_starts_with($styleName, '@')) {
+                    usort($childPath, self::compareSelectorParts(...));
                 }
-                $subSelectors[] = $this->renderProperties($styleValue, $childPath);
+                $subSelectors[] = $this->renderProperties((array)$styleValue, $childPath);
             } elseif ($styleValue !== null && $styleValue !== '') {
                 $styleProps[]= $styleName . ':' . $styleValue;
             }
@@ -96,15 +92,11 @@ protected function renderProperties(array $properties, array $path = []): string
 
     /**
      * Sorts a CSS selector to keep media queries at the start of the given array
-     *
-     * @param string $a
-     * @param string $b
-     * @return int
      */
     private static function compareSelectorParts(string $a, string $b): int
     {
-        $aIsMediaQuery = strpos($a, '@') === 0;
-        $bIsMediaQuery = strpos($b, '@') === 0;
+        $aIsMediaQuery = str_starts_with($a, '@');
+        $bIsMediaQuery = str_starts_with($b, '@');
         if ($aIsMediaQuery && !$bIsMediaQuery) {
             return -1;
         }
diff --git a/Tests/Functional/Fixtures/Fusion/example.css b/Resources/Private/Tests/example.css
similarity index 100%
rename from Tests/Functional/Fixtures/Fusion/example.css
rename to Resources/Private/Tests/example.css
diff --git a/Tests/Functional/AbstractFusionStylingTestCase.php b/Tests/Functional/AbstractFusionStylingTestCase.php
new file mode 100644
index 0000000..c3c4d8e
--- /dev/null
+++ b/Tests/Functional/AbstractFusionStylingTestCase.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shel\CriticalCSS\Tests\Functional;
+
+/*
+ * This file is part of the Shel.CriticalCSS package.
+ */
+
+use GuzzleHttp\Psr7\ServerRequest;
+use Neos\Flow\Mvc\ActionRequest;
+use Neos\Fusion\Core\FusionGlobals;
+use Neos\Fusion\Core\FusionSourceCodeCollection;
+use Neos\Fusion\Core\RuntimeFactory;
+use Neos\Fusion\Tests\Functional\FusionObjects\AbstractFusionObjectTest;
+use Neos\Fusion\Tests\Functional\FusionObjects\TestingViewForFusionRuntime;
+
+/**
+ * Abstract testcase for the style collector object
+ */
+abstract class AbstractFusionStylingTestCase extends AbstractFusionObjectTest
+{
+    protected function buildView(): TestingViewForFusionRuntime
+    {
+        $this->request = ActionRequest::fromHttpRequest(new ServerRequest('GET', 'http://localhost/'));
+
+        $runtime = $this->objectManager->get(RuntimeFactory::class)->createFromSourceCode(
+            FusionSourceCodeCollection::fromFilePath(__DIR__ . '/Fixtures/Fusion/Root.fusion'),
+            FusionGlobals::fromArray(['request' => $this->request])
+        );
+
+        $view = new TestingViewForFusionRuntime($runtime);
+        $view->assign('fixtureDirectory', __DIR__ . '/Fixtures/');
+        return $view;
+    }
+}
diff --git a/Tests/Functional/Fixtures/Fusion/Common.fusion b/Tests/Functional/Fixtures/Fusion/Common.fusion
new file mode 100644
index 0000000..31687fb
--- /dev/null
+++ b/Tests/Functional/Fixtures/Fusion/Common.fusion
@@ -0,0 +1,7 @@
+prototype(Neos.Fusion:Tag).@class = 'Neos\\Fusion\\FusionObjects\\TagImplementation'
+prototype(Neos.Fusion:TestRenderer).@class = 'Neos\\Fusion\\Tests\\Functional\\View\\Fixtures\\TestRenderer'
+prototype(Neos.Fusion:DataStructure).@class = 'Neos\\Fusion\\FusionObjects\\DataStructureImplementation'
+
+prototype(Shel.CriticalCSS:LoadStyles).@class = 'Shel\\CriticalCSS\\FusionObjects\\LoadStylesImplementation'
+prototype(Shel.CriticalCSS:StyleCollector).@class = 'Shel\\CriticalCSS\\FusionObjects\\StyleCollectorImplementation'
+prototype(Shel.CriticalCSS:Styles).@class = 'Shel\\CriticalCSS\\FusionObjects\\StylesImplementation'
diff --git a/Tests/Functional/Fixtures/Fusion/LoadStyles.fusion b/Tests/Functional/Fixtures/Fusion/LoadStyles.fusion
index 0a59e9e..1258150 100644
--- a/Tests/Functional/Fixtures/Fusion/LoadStyles.fusion
+++ b/Tests/Functional/Fixtures/Fusion/LoadStyles.fusion
@@ -1,18 +1,9 @@
-prototype(Shel.CriticalCSS:LoadStyles).@class = 'Shel\\CriticalCSS\\FusionObjects\\LoadStylesImplementation'
-prototype(Neos.Fusion:Tag).@class = 'Neos\\Fusion\\FusionObjects\\TagImplementation'
-prototype(Neos.Fusion:TestRenderer).@class = 'Neos\\Fusion\\Tests\\Functional\\View\\Fixtures\\TestRenderer'
-
 styleLoader.insertStyles = Shel.CriticalCSS:LoadStyles {
-    path = 'Packages/Plugins/Shel.CriticalCSS/Tests/Functional/Fixtures/Fusion/example.css'
-}
-
-styleLoader.prependStyles = Shel.CriticalCSS:LoadStyles {
-    path = 'Packages/Plugins/Shel.CriticalCSS/Tests/Functional/Fixtures/Fusion/example.css'
-    content = '<div>foo</div>'
+    path = 'resource://Shel.CriticalCSS/Private/Tests/example.css'
 }
 
 styleLoader.prependStyles = Shel.CriticalCSS:LoadStyles {
-    path = 'Packages/Plugins/Shel.CriticalCSS/Tests/Functional/Fixtures/Fusion/example.css'
+    path = 'resource://Shel.CriticalCSS/Private/Tests/example.css'
     content = '<div>foo</div>'
 }
 
@@ -20,6 +11,6 @@ styleLoader.asProcess = Neos.Fusion:Tag {
     content = 'foo'
     @process.style = Shel.CriticalCSS:LoadStyles {
         content = ${value}
-        path = 'Packages/Plugins/Shel.CriticalCSS/Tests/Functional/Fixtures/Fusion/example.css'
+        path = 'resource://Shel.CriticalCSS/Private/Tests/example.css'
     }
 }
diff --git a/Tests/Functional/Fixtures/Fusion/Root.fusion b/Tests/Functional/Fixtures/Fusion/Root.fusion
new file mode 100644
index 0000000..a92a174
--- /dev/null
+++ b/Tests/Functional/Fixtures/Fusion/Root.fusion
@@ -0,0 +1 @@
+include: **/*
diff --git a/Tests/Functional/Fixtures/Fusion/StyleCollector.fusion b/Tests/Functional/Fixtures/Fusion/StyleCollector.fusion
index cf69b5b..816822e 100644
--- a/Tests/Functional/Fixtures/Fusion/StyleCollector.fusion
+++ b/Tests/Functional/Fixtures/Fusion/StyleCollector.fusion
@@ -1,6 +1,3 @@
-prototype(Shel.CriticalCSS:StyleCollector).@class = 'Shel\\CriticalCSS\\FusionObjects\\StyleCollectorImplementation'
-prototype(Neos.Fusion:TestRenderer).@class = 'Neos\\Fusion\\Tests\\Functional\\View\\Fixtures\\TestRenderer'
-
 styleCollector.collectMultipleStyles = Shel.CriticalCSS:StyleCollector {
     content = '
         <html>
diff --git a/Tests/Functional/Fixtures/Fusion/Styles.fusion b/Tests/Functional/Fixtures/Fusion/Styles.fusion
index a105cf2..4c1f272 100644
--- a/Tests/Functional/Fixtures/Fusion/Styles.fusion
+++ b/Tests/Functional/Fixtures/Fusion/Styles.fusion
@@ -1,7 +1,3 @@
-prototype(Shel.CriticalCSS:Styles).@class = 'Shel\\CriticalCSS\\FusionObjects\\StylesImplementation'
-prototype(Neos.Fusion:DataStructure).@class = 'Neos\\Fusion\\FusionObjects\\DataStructureImplementation'
-prototype(Neos.Fusion:TestRenderer).@class = 'Neos\\Fusion\\Tests\\Functional\\View\\Fixtures\\TestRenderer'
-
 styles.basic = Shel.CriticalCSS:Styles {
     @content = '<div>foo</div>'
     color = 'green'
diff --git a/Tests/Functional/StyleCollectorTest.php b/Tests/Functional/StyleCollectorTest.php
index c384fdc..472708b 100644
--- a/Tests/Functional/StyleCollectorTest.php
+++ b/Tests/Functional/StyleCollectorTest.php
@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 namespace Shel\CriticalCSS\Tests\Functional;
@@ -7,68 +8,48 @@
  * This file is part of the Shel.CriticalCSS package.
  */
 
-use Neos\Fusion\Tests\Functional\FusionObjects\AbstractFusionObjectTest;
-use Neos\Fusion\View\FusionView;
-
 /**
  * Testcase for the style collector object
  */
-class StyleCollectorTest extends AbstractFusionObjectTest
+class StyleCollectorTest extends AbstractFusionStylingTestCase
 {
-    /**
-     * @inheritDoc
-     */
-    protected function buildView(): FusionView
-    {
-        $view = parent::buildView();
-        $view->setPackageKey('Shel.CriticalCSS');
-        $view->setFusionPathPattern(__DIR__ . '/Fixtures/Fusion');
-        return $view;
-    }
-
     /**
      * @test
      */
-    public function collectMultipleStylesWorks()
+    public function collectMultipleStylesWorks(): void
     {
-        $view = $this->buildView();
-
-        $view->setFusionPath('styleCollector/collectMultipleStyles');
-        $this->assertEquals(
+        $this->assertFusionPath(
             '
         <html>
             <head>
                 <title>Test</title>
             <style>.foo{color:blue}.bar{color:green}</style></head>
             <body>
-                
                 <div class="foo">foo</div>
-                
                 <div class="bar">bar</div>
             </body>
-        </html>', $view->render());
+        </html>',
+            'styleCollector/collectMultipleStyles'
+        );
     }
 
     /**
      * @test
      */
-    public function removeDuplicatesStylesWorks()
+    public function removeDuplicatesStylesWorks(): void
     {
-        $view = $this->buildView();
-
-        $view->setFusionPath('styleCollector/removeDuplicatesStyles');
-        $this->assertEquals(
+        $this->assertFusionPath(
             '
         <html>
             <head>
                 <title>Test</title>
             <style>.foo{color:blue}</style></head>
             <body>
-                
                 <div class="foo">foo</div>
-                
                 <div class="foo">foo</div>
             </body>
-        </html>', $view->render());
+        </html>',
+            'styleCollector/removeDuplicatesStyles'
+        );
     }
 }
diff --git a/Tests/Functional/StyleLoaderTest.php b/Tests/Functional/StyleLoaderTest.php
index f328e4e..586c94e 100644
--- a/Tests/Functional/StyleLoaderTest.php
+++ b/Tests/Functional/StyleLoaderTest.php
@@ -7,67 +7,45 @@
  * This file is part of the Shel.CriticalCSS package.
  */
 
-use Neos\Fusion\Tests\Functional\FusionObjects\AbstractFusionObjectTest;
-use Neos\Fusion\View\FusionView;
-
 /**
  * Testcase for the style loader object
  */
-class StyleLoaderTest extends AbstractFusionObjectTest
+class StyleLoaderTest extends AbstractFusionStylingTestCase
 {
-    /**
-     * @inheritDoc
-     */
-    protected function buildView(): FusionView
-    {
-        $view = parent::buildView();
-        $view->setPackageKey('Shel.CriticalCSS');
-        $view->setFusionPathPattern(__DIR__ . '/Fixtures/Fusion');
-        return $view;
-    }
 
     /**
      * @test
      */
-    public function insertingStylesWorks()
+    public function insertingStylesWorks(): void
     {
-        $view = $this->buildView();
-
-        $view->setFusionPath('styleLoader/insertStyles');
-        $this->assertEquals(
+        $this->assertFusionPath(
             '<style data-inline>.foo {
     color: blue;
 }
-</style>', $view->render());
+</style>', 'styleLoader/insertStyles');
     }
 
     /**
      * @test
      */
-    public function prependingStylesWorks()
+    public function prependingStylesWorks(): void
     {
-        $view = $this->buildView();
-
-        $view->setFusionPath('styleLoader/prependStyles');
-        $this->assertEquals(
+        $this->assertFusionPath(
             '<style data-inline>.foo {
     color: blue;
 }
-</style><div>foo</div>', $view->render());
+</style><div>foo</div>', 'styleLoader/prependStyles');
     }
 
     /**
      * @test
      */
-    public function addStylesAsProcessWorks()
+    public function addStylesAsProcessWorks(): void
     {
-        $view = $this->buildView();
-
-        $view->setFusionPath('styleLoader/asProcess');
-        $this->assertEquals(
+        $this->assertFusionPath(
             '<style data-inline>.foo {
     color: blue;
 }
-</style><div>foo</div>', $view->render());
+</style><div>foo</div>', 'styleLoader/asProcess');
     }
 }
diff --git a/Tests/Functional/StylesTest.php b/Tests/Functional/StylesTest.php
index e7d5779..4e31c2e 100644
--- a/Tests/Functional/StylesTest.php
+++ b/Tests/Functional/StylesTest.php
@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 namespace Shel\CriticalCSS\Tests\Functional;
@@ -7,24 +8,11 @@
  * This file is part of the Shel.CriticalCSS package.
  */
 
-use Neos\Fusion\Tests\Functional\FusionObjects\AbstractFusionObjectTest;
-use Neos\Fusion\View\FusionView;
-
 /**
  * Testcase for the styles object
  */
-class StylesTest extends AbstractFusionObjectTest
+class StylesTest extends AbstractFusionStylingTestCase
 {
-    /**
-     * @inheritDoc
-     */
-    protected function buildView(): FusionView
-    {
-        $view = parent::buildView();
-        $view->setPackageKey('Shel.CriticalCSS');
-        $view->setFusionPathPattern(__DIR__ . '/Fixtures/Fusion');
-        return $view;
-    }
 
     /**
      * @test
@@ -38,7 +26,8 @@ public function basicRenderingWorks()
             '<style data-inline>' .
             '.style--1d5b3fc659{color:green;font-size:12px}' .
             '</style>' .
-            '<div class="style--1d5b3fc659">foo</div>', $view->render()
+            '<div class="style--1d5b3fc659">foo</div>',
+            $view->render()
         );
     }
 
@@ -70,7 +59,8 @@ public function eelExpressionRenderingWorks()
             '<style data-inline>' .
             '.style--a01f4ebd21{font-size:7px}' .
             '</style>' .
-            '<div class="style--a01f4ebd21">foo</div>', $view->render()
+            '<div class="style--a01f4ebd21">foo</div>',
+            $view->render()
         );
     }
 
@@ -87,7 +77,8 @@ public function nestedRenderingWorks()
             '.style--0e1e7d5620{color:blue}' .
             '.style--0e1e7d5620 strong{font-weight:bold}' .
             '</style>' .
-            '<div class="style--0e1e7d5620">foo <strong>bar</strong></div>', $view->render()
+            '<div class="style--0e1e7d5620">foo <strong>bar</strong></div>',
+            $view->render()
         );
     }
 
@@ -105,7 +96,8 @@ public function nestedRenderingWithoutDataStructuresWorks()
             '.style--e2384db9d9 strong{font-weight:bold}' .
             '.style--e2384db9d9 strong em{color:pink}' .
             '</style>' .
-            '<div class="style--e2384db9d9">foo <strong>bar <em>pony</em></strong></div>', $view->render()
+            '<div class="style--e2384db9d9">foo <strong>bar <em>pony</em></strong></div>',
+            $view->render()
         );
     }
 
@@ -123,7 +115,8 @@ public function nestedEvaluationRenderingWorks()
             '.style--385286f4a7 strong{font-weight:bold}' .
             '.style--385286f4a7 strong em{margin-top:50px}' .
             '</style>' .
-            '<div class="style--385286f4a7">foo <strong>bar <em>pony</em></strong></div>', $view->render()
+            '<div class="style--385286f4a7">foo <strong>bar <em>pony</em></strong></div>',
+            $view->render()
         );
     }
 
@@ -139,7 +132,8 @@ public function selectorRenderingWorks()
             '<style data-inline>' .
             'body{font-family:Comic Sans}' .
             '</style>' .
-            '<html><body>foo</body></html>', $view->render()
+            '<html><body>foo</body></html>',
+            $view->render()
         );
     }
 
@@ -156,7 +150,8 @@ public function mediaQueryRenderingWorks()
             '.style--3e741db00a{color:blue}' .
             '@media all{.style--3e741db00a{color:green}}' .
             '</style>' .
-            '<div class="style--3e741db00a">foo</div>', $view->render()
+            '<div class="style--3e741db00a">foo</div>',
+            $view->render()
         );
     }
 
@@ -174,7 +169,8 @@ public function mediaQueryWithNestingRenderingWorks()
             '@media all{.style--751ebabd93{color:green}}' .
             '@media all{.style--751ebabd93 strong{color:yellow}}' .
             '</style>' .
-            '<div class="style--751ebabd93">foo <strong>bar</strong></div>', $view->render()
+            '<div class="style--751ebabd93">foo <strong>bar</strong></div>',
+            $view->render()
         );
     }
 
@@ -195,7 +191,8 @@ public function nestedMediaQueriesRenderingWorks()
             '.style--2d1e5ab0be strong{display:block}' .
             '}}' .
             '</style>' .
-            '<div class="style--2d1e5ab0be">foo <strong>bar</strong></div>', $view->render()
+            '<div class="style--2d1e5ab0be">foo <strong>bar</strong></div>',
+            $view->render()
         );
     }
 
@@ -217,7 +214,8 @@ public function supportsQueryRenderingWorks()
             'display:flex' .
             '}}' .
             '</style>' .
-            '<div class="style--c07e794268">foo</div>', $view->render()
+            '<div class="style--c07e794268">foo</div>',
+            $view->render()
         );
     }
 }
diff --git a/composer.json b/composer.json
index 51d6348..ee3a311 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,8 @@
       "Components"
     ],
     "require": {
-        "neos/neos": "~7.0 || ~8.0 || dev-master"
+        "php": ">=8.2",
+        "neos/neos": "^9.0"
     },
     "authors": [
       {
@@ -32,9 +33,20 @@
             "Shel\\CriticalCSS\\Tests\\": "Tests"
         }
     },
+    "scripts": {
+        "test": "../../../bin/phpunit --enforce-time-limit --bootstrap ../../Libraries/autoload.php --testdox Tests",
+        "test:ci": "phpunit --enforce-time-limit --bootstrap vendor/autoload.php --testdox Tests",
+        "codestyle": "phpstan analyse --autoload-file ../../Libraries/autoload.php",
+        "codestyle:ci": "phpstan analyse"
+    },
     "extra": {
         "neos": {
             "package-key": "Shel.CriticalCSS"
         }
+    },
+    "config": {
+        "allow-plugins": {
+            "neos/composer-plugin": true
+        }
     }
 }
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..ad9bda7
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,7 @@
+parameters:
+    level: 8
+    paths:
+        - Classes
+    ignoreErrors:
+#        - '#Call to an undefined method [a-zA-Z0-9\\_]+Repository::findBy[a-zA-Z]+\(\)#'
+        - '#Call to an undefined method [a-zA-Z0-9\\_]+Repository::findOneBy[a-zA-Z]+\(\)#'