[TASK] Add CSS class for TYPO3 12 to allow backporting of some design

Classes/ViewHelpers/Condition/IsTypo3TwelveViewHelper.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+namespace In2code\Lux\ViewHelpers\Condition;
+
+use In2code\Lux\Utility\ConfigurationUtility;
+use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
+use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractConditionViewHelper;
+
+/**
+ * @noinspection PhpUnused
+ * Todo: Can be removed when TYPO3 12 support is dropped
+ */
+class IsTypo3TwelveViewHelper extends AbstractConditionViewHelper
+{
+    public static function verdict(array $arguments, RenderingContextInterface $renderingContext)
+    {
+        return ConfigurationUtility::isTypo3Version12();
+    }
+}

Resources/Private/Layouts/Backend.html

@@ -8,7 +8,7 @@
 <div class="module">
     <f:render partial="DocHeader" arguments="{docHeader:docHeader}" />
 
-    <div class="module-body lux">
+    <div class="module-body lux{lux:condition.isTypo3Twelve(then:' lux--12')}">
         <f:render partial="Miscellaneous/FlashMessages" arguments="{_all}"/>
 
         <f:if condition="{filter} && !{filter.anyAllowedSites}">

Resources/Private/Templates/Backend/PageOverview.html

@@ -8,7 +8,7 @@
         0: '{f:uri.resource(path:\'Css/PageOverview.min.css\',extensionName:\'Lux\')}'
     }"/>
 
-    <div class="lux lux-pageoverview-container">
+    <div class="lux lux-pageoverview-container{lux:condition.isTypo3Twelve(then:' lux--12')}">
         <div class="lux-pageoverview-container-inner">
             <lux:condition.isLuxenterpriseExtensionActivated>
                 <f:else>