diff --git a/.travis.yml b/.travis.yml
index 98c1bbe..57bb81a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,7 @@
 language: php
 
 php:
-    - 7.2
-    - 7.3
-    - 7.4
+    - 8.0
 
 before_install:
     - composer self-update
@@ -14,7 +12,7 @@ install:
 script:
     - composer cs:check
     - composer phpstan:check
-    - composer tests
+    - composer tester:check
 
 after_success:
     - wget https://github.com/satooshi/php-coveralls/releases/download/v1.0.1/coveralls.phar
diff --git a/Dockerfile b/Dockerfile
index ceaa795..c3037a9 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,11 +1,14 @@
-FROM php:7.2
+FROM php:8.0
 
 LABEL maintainer="8machy@seznam.cz"
 
 ENV PATH "/composer/vendor/bin:$PATH"
 ENV COMPOSER_ALLOW_SUPERUSER 1
 
-RUN apt-get update && apt-get install -y curl curl git zip unzip
+RUN apt-get update && apt-get install -y curl curl git zip unzip \
+	&& apt-get install -y libicu-dev \
+	&& docker-php-ext-configure intl \
+	&& docker-php-ext-install intl
 
 RUN curl -s https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
 
diff --git a/composer.json b/composer.json
index 25c5d21..10bb15b 100644
--- a/composer.json
+++ b/composer.json
@@ -4,17 +4,18 @@
 	"keywords": ["webloader", "module-bundler", "javascript", "css", "frontend", "build-tool"],
 	"license": "BSD-3-Clause",
 	"require": {
-		"php": ">=7.2",
+		"php": ">=8.0",
 		"nette/neon": "^2.4|^3.0"
 	},
 	"require-dev": {
-		"tracy/tracy": "^2.7",
-		"nette/tester": "^2.3",
+		"tracy/tracy": "^2.8",
+		"nette/tester": "^2.4",
 		"tubalmartin/cssmin": "^4.1",
 		"machy8/google-closure-compiler": "^1.0",
 		"phpstan/phpstan": "^0.12",
-		"symplify/easy-coding-standard": "^8.2",
-		"migrify/config-transformer": "^0.3.26"
+		"symplify/easy-coding-standard": "^9.2",
+		"symplify/config-transformer": "^9.2",
+		"nette/di": "^3.0"
 	},
 	"suggest": {
 		"machy8/google-closure-compiler": "PHP client for the Google Closure Compiler API in one file",
@@ -26,13 +27,13 @@
 	},
 	"extra": {
 		"branch-alias": {
-			"dev-master": "1.4-dev"
+			"dev-master": "2.0-dev"
 		}
 	},
 	"scripts": {
-		"cs:check": "vendor/bin/ecs check src --set psr12",
-		"cs:fix": "vendor/bin/ecs check src --set psr12 --fix",
-		"phpstan:check": "phpstan analyse -c tests/phpstan/phpstan.neon -l max src tests/nette-tester",
+		"cs:check": "vendor/bin/ecs check src -c tests/coding-standard/ecs.php",
+		"cs:fix": "vendor/bin/ecs check src -c tests/coding-standard/ecs.php",
+		"phpstan:check": "phpstan analyse -c tests/phpstan/phpstan.neon -l 5 src tests/nette-tester",
 		"tester:check": "tester -p phpdbg tests/nette-tester -s --coverage ./coverage.xml --coverage-src ./src"
 	},
 	"minimum-stability": "dev",
diff --git a/docker-compose.yml b/docker-compose.yml
index 55d8d75..3903c52 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,6 +1,6 @@
 version: "3"
 services:
-    webloader:
+    server:
         container_name: webloader
         working_dir: /var/www/html
         build: .
diff --git a/src/Bridges/Nette/WebLoaderExtension.php b/src/Bridges/Nette/WebLoaderExtension.php
index 56276aa..216bda6 100644
--- a/src/Bridges/Nette/WebLoaderExtension.php
+++ b/src/Bridges/Nette/WebLoaderExtension.php
@@ -19,14 +19,13 @@
 
 class WebLoaderExtension extends CompilerExtension
 {
-    private const
-        ENGINE_CLASSNAME = 'WebLoader\Engine',
-        ENGINE_PREFIX = 'engine',
+    private const ENGINE_CLASSNAME = 'WebLoader\Engine';
+    private const ENGINE_PREFIX = 'engine';
 
-        TRACY_CLASSNAME = 'Tracy\Debugger',
+    private const TRACY_CLASSNAME = 'Tracy\Debugger';
 
-        TRACY_PANEL_CLASSNAME = 'WebLoader\Bridges\Tracy\WebLoaderPanel',
-        TRACY_PANEL_PREFIX = 'tracyPanel';
+    private const TRACY_PANEL_CLASSNAME = 'WebLoader\Bridges\Tracy\WebLoaderPanel';
+    private const TRACY_PANEL_PREFIX = 'tracyPanel';
 
     /**
      * @var array
diff --git a/src/WebLoader/Engine.php b/src/WebLoader/Engine.php
index 22f17d1..b42592c 100644
--- a/src/WebLoader/Engine.php
+++ b/src/WebLoader/Engine.php
@@ -15,24 +15,23 @@
 
 class Engine
 {
-    public const
-        CSS = 'css',
-        JS = 'js';
+    public const CSS = 'css';
+    public const JS = 'js';
 
     /**
      * @var Compiler
      */
-    private $compiler;
+    private $compiler = null;
 
     /**
      * @var FilesCollectionRender
      */
-    private $filesCollectionRender;
+    private $filesCollectionRender = null;
 
     /**
      * @var FilesCollectionsContainerRender
      */
-    private $filesCollectionsContainerRender;
+    private $filesCollectionsContainerRender = null;
 
 
     public function __construct(string $outputDir, string $documentRoot = '/', ?string $publicPathPrefix = null)
@@ -120,7 +119,7 @@ public function disableCache(): Engine
 
     public function getCompiler(): Compiler
     {
-        if (!$this->compiler) {
+        if ($this->compiler === null) {
             $this->compiler = new Compiler();
         }
 
@@ -130,7 +129,7 @@ public function getCompiler(): Compiler
 
     public function getFilesCollectionRender(): FilesCollectionRender
     {
-        if (!$this->filesCollectionRender) {
+        if ($this->filesCollectionRender === null) {
             $this->filesCollectionRender = new FilesCollectionRender($this->getCompiler());
         }
 
@@ -140,7 +139,7 @@ public function getFilesCollectionRender(): FilesCollectionRender
 
     public function getFilesCollectionsContainerRender(): FilesCollectionsContainerRender
     {
-        if (!$this->filesCollectionsContainerRender) {
+        if ($this->filesCollectionsContainerRender === null) {
             $this->filesCollectionsContainerRender = new FilesCollectionsContainerRender(
                 $this->getFilesCollectionRender()
             );
diff --git a/src/WebLoader/FilesCollection.php b/src/WebLoader/FilesCollection.php
index 2fb22ca..5703b01 100644
--- a/src/WebLoader/FilesCollection.php
+++ b/src/WebLoader/FilesCollection.php
@@ -15,15 +15,14 @@
 
 class FilesCollection
 {
-    public const
-        CONFIG_SECTION_CSS_FILES = Engine::CSS . 'Files',
-        CONFIG_SECTION_CSS_FILTERS = Engine::CSS . 'Filters',
-        CONFIG_SECTION_CSS_LOAD_CONTENT = Engine::CSS . 'LoadContent',
-        CONFIG_SECTION_CSS_OUTPUT_ELEMENT_ATTRIBUTES = Engine::CSS . 'OutputElementAttributes',
-        CONFIG_SECTION_JS_FILES = Engine::JS . 'Files',
-        CONFIG_SECTION_JS_FILTERS = Engine::JS . 'Filters',
-        CONFIG_SECTION_JS_LOAD_CONTENT = Engine::JS . 'LoadContent',
-        CONFIG_SECTION_JS_OUTPUT_ELEMENT_ATTRIBUTES = Engine::JS . 'OutputElementAttributes';
+    public const CONFIG_SECTION_CSS_FILES = Engine::CSS . 'Files';
+    public const CONFIG_SECTION_CSS_FILTERS = Engine::CSS . 'Filters';
+    public const CONFIG_SECTION_CSS_LOAD_CONTENT = Engine::CSS . 'LoadContent';
+    public const CONFIG_SECTION_CSS_OUTPUT_ELEMENT_ATTRIBUTES = Engine::CSS . 'OutputElementAttributes';
+    public const CONFIG_SECTION_JS_FILES = Engine::JS . 'Files';
+    public const CONFIG_SECTION_JS_FILTERS = Engine::JS . 'Filters';
+    public const CONFIG_SECTION_JS_LOAD_CONTENT = Engine::JS . 'LoadContent';
+    public const CONFIG_SECTION_JS_OUTPUT_ELEMENT_ATTRIBUTES = Engine::JS . 'OutputElementAttributes';
 
     /**
      * @var array
diff --git a/src/WebLoader/FilesCollectionRender.php b/src/WebLoader/FilesCollectionRender.php
index 40787f1..b9fb783 100644
--- a/src/WebLoader/FilesCollectionRender.php
+++ b/src/WebLoader/FilesCollectionRender.php
@@ -15,20 +15,19 @@
 
 class FilesCollectionRender
 {
-    private const
-        LINK_ELEMENT = 'link',
-        SCRIPT_ELEMENT = 'script',
-        STYLE_ELEMENT = 'style',
+    private const LINK_ELEMENT = 'link';
+    private const SCRIPT_ELEMENT = 'script';
+    private const STYLE_ELEMENT = 'style';
 
-        LINK_PREFETCH = 'prefetch',
-        LINK_PRELOAD = 'preload',
-        LINK_PRELOAD_AS_CSS = 'style',
-        LINK_PRELOAD_AS_JS = 'script',
+    private const LINK_PREFETCH = 'prefetch';
+    private const LINK_PRELOAD = 'preload';
+    private const LINK_PRELOAD_AS_CSS = 'style';
+    private const LINK_PRELOAD_AS_JS = 'script';
 
-        SCRIPT_TYPE_ATTRIBUTE = 'text/javascript',
-        STYLE_TYPE_ATTRIBUTE = 'text/css',
+    private const SCRIPT_TYPE_ATTRIBUTE = 'text/javascript';
+    private const STYLE_TYPE_ATTRIBUTE = 'text/css';
 
-        VERSION_MARK = '?v=';
+    private const VERSION_MARK = '?v=';
 
     /**
      * @var Compiler
@@ -88,7 +87,7 @@ public function css(?string $collectionName = null, array $attributes = [], bool
      */
     public function cssPrefetch($collectionsNames = null): string
     {
-        return $this->generateMetaLinkElements($collectionsNames, Engine::CSS, self::LINK_PREFETCH);
+        return $this->generateMetaLinkElements(Engine::CSS, self::LINK_PREFETCH, $collectionsNames);
     }
 
 
@@ -99,9 +98,9 @@ public function cssPrefetch($collectionsNames = null): string
     public function cssPreload($collectionsNames = null): string
     {
         return $this->generateMetaLinkElements(
-            $collectionsNames,
             Engine::CSS,
             self::LINK_PRELOAD,
+            $collectionsNames,
             self::LINK_PRELOAD_AS_CSS
         );
     }
@@ -140,7 +139,7 @@ public function js(?string $collectionName = null, array $attributes = [], bool
      */
     public function jsPrefetch($collectionsNames = null): string
     {
-        return $this->generateMetaLinkElements($collectionsNames, Engine::JS, self::LINK_PREFETCH);
+        return $this->generateMetaLinkElements(Engine::JS, self::LINK_PREFETCH, $collectionsNames);
     }
 
 
@@ -151,9 +150,9 @@ public function jsPrefetch($collectionsNames = null): string
     public function jsPreload($collectionsNames = null): string
     {
         return $this->generateMetaLinkElements(
-            $collectionsNames,
             Engine::JS,
             self::LINK_PRELOAD,
+            $collectionsNames,
             self::LINK_PRELOAD_AS_JS
         );
     }
@@ -223,9 +222,9 @@ private function generateElement(string $element, array $attributes, ?string $fi
      * @param array|string|NULL $collectionsNames
      */
     private function generateMetaLinkElements(
-        $collectionsNames = null,
         string $collectionsType,
         string $rel,
+        $collectionsNames = null,
         ?string $as = null
     ): string {
         $tags = '';
diff --git a/src/WebLoader/FilesCollectionsContainer.php b/src/WebLoader/FilesCollectionsContainer.php
index 32bd87a..9896731 100644
--- a/src/WebLoader/FilesCollectionsContainer.php
+++ b/src/WebLoader/FilesCollectionsContainer.php
@@ -15,9 +15,8 @@
 
 class FilesCollectionsContainer
 {
-    public const
-        CONFIG_SECTION_CSS_COLLECTIONS = Engine::CSS . 'Collections',
-        CONFIG_SECTION_JS_COLLECTIONS = Engine::JS . 'Collections';
+    public const CONFIG_SECTION_CSS_COLLECTIONS = Engine::CSS . 'Collections';
+    public const CONFIG_SECTION_JS_COLLECTIONS = Engine::JS . 'Collections';
 
     /**
      * @var string[]
diff --git a/src/WebLoader/Filters/CssBreakpointsFilter.php b/src/WebLoader/Filters/CssBreakpointsFilter.php
index 0750f2c..d500119 100644
--- a/src/WebLoader/Filters/CssBreakpointsFilter.php
+++ b/src/WebLoader/Filters/CssBreakpointsFilter.php
@@ -15,9 +15,8 @@
 
 class CssBreakpointsFilter
 {
-    private const
-        MEDIA_QUERIES_REGULAR_EXPRESSION = '~@media(?<parameters>[^{]+){(?:[^{}]*{[^{}]*})+[^}]+}~',
-        MIN_WIDTH_REGULAR_EXPRESSION = '~\(min-width\s*:\s*(?<value>\d+)\s*(?<unit>\S+)\)~';
+    private const MEDIA_QUERIES_REGULAR_EXPRESSION = '~@media(?<parameters>[^{]+){(?:[^{}]*{[^{}]*})+[^}]+}~';
+    private const MIN_WIDTH_REGULAR_EXPRESSION = '~\(min-width\s*:\s*(?<value>\d+)\s*(?<unit>\S+)\)~';
 
     /**
      * @var array
diff --git a/src/WebLoader/Filters/CssUrlFilter.php b/src/WebLoader/Filters/CssUrlFilter.php
index 33764a4..03f965f 100644
--- a/src/WebLoader/Filters/CssUrlFilter.php
+++ b/src/WebLoader/Filters/CssUrlFilter.php
@@ -15,9 +15,8 @@
 
 class CssUrlFilter
 {
-    private const
-        URL_REGEXP = '~url\([\'"]*(?<url>(?!(?:data:|.*//))[^\'"]+)[\'"]*\)~U',
-        ABSOLUTE_PATH_REGEXP = '~^/~U';
+    private const URL_REGEXP = '~url\([\'"]*(?<url>(?!(?:data:|.*//))[^\'"]+)[\'"]*\)~U';
+    private const ABSOLUTE_PATH_REGEXP = '~^/~U';
 
     /**
      * @var string
@@ -39,7 +38,7 @@ public function __construct(string $outputDirPath, string $documentRoot = '/')
     }
 
 
-    public function filter(string $code, string $filePath): string
+    public function filter(string $code, string $filePath): ?string
     {
         $filePath = ltrim($filePath, '/');
         $pathInfo = str_replace($this->documentRoot, '', pathinfo($filePath)['dirname']);
diff --git a/tests/coding-standard/ecs.php b/tests/coding-standard/ecs.php
new file mode 100755
index 0000000..ec65783
--- /dev/null
+++ b/tests/coding-standard/ecs.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpCsFixer\Fixer\ArrayNotation\ArraySyntaxFixer;
+use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+use Symplify\EasyCodingStandard\ValueObject\Option;
+use Symplify\EasyCodingStandard\ValueObject\Set\SetList;
+
+return static function (ContainerConfigurator $containerConfigurator): void {
+    $services = $containerConfigurator->services();
+    $services->set(ArraySyntaxFixer::class)
+        ->call('configure', [[
+            'syntax' => 'short',
+        ]]);
+
+    $parameters = $containerConfigurator->parameters();
+    $parameters->set(Option::PATHS, [
+        __DIR__ . '/src',
+        __DIR__ . '/tests',
+    ]);
+
+    $parameters->set(Option::SETS, [
+        SetList::PSR_12
+    ]);
+};
diff --git a/tests/phpstan/phpstan.neon b/tests/phpstan/phpstan.neon
index 2832fd2..5dce781 100644
--- a/tests/phpstan/phpstan.neon
+++ b/tests/phpstan/phpstan.neon
@@ -3,4 +3,3 @@ parameters:
 		- ../nette-tester/AbstractTestCase.php
 	ignoreErrors:
 		- '#Property [a-zA-Z0-9\\_]+::\$[a-zA-Z0-9_]+ \([\S]+\) does not accept [\S\|]+\.#'
-		- '#Argument of an invalid type array\|string\|null supplied for foreach, only iterables are supported.#'