diff --git a/composer.json b/composer.json
index fec0190..1e2bc6d 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
         "nette/neon": "^3.4",
         "nikic/php-parser": "^5.7",
         "phiki/phiki": "^2.1",
-        "php-collective/djot": "^0.1.15",
+        "php-collective/djot": "^0.1.21",
         "php": ">=8.2",
         "symfony/process": "^7.3"
     },
diff --git a/src/Render/Djot/CodeGroupExtension.php b/src/Render/Djot/CodeGroupExtension.php
index d3fa600..64a302c 100644
--- a/src/Render/Djot/CodeGroupExtension.php
+++ b/src/Render/Djot/CodeGroupExtension.php
@@ -13,6 +13,12 @@
 
 /**
  * Djot extension that renders `::: code-group` blocks as tabbed code panes.
+ *
+ * Supports language hints with optional `[label]` suffix:
+ * - `php` -> language: php, label: php
+ * - `php [Installation]` -> language: php, label: Installation
+ * - `[Custom Label]` -> language: null, label: Custom Label
+ * - `c++`, `c#`, `text/html` -> works with special characters
  */
 final class CodeGroupExtension implements ExtensionInterface
 {
@@ -52,7 +58,7 @@ public function register(DjotConverter $converter): void
                 return;
             }
 
-            $event->setHtml($this->renderCodeGroup($codeBlocks));
+            $event->setHtml($this->renderCodeGroup($node, $codeBlocks));
         });
     }
 
@@ -96,14 +102,17 @@ protected function extractCodeBlocks(Div $node): array
     /**
      * Render grouped code blocks as a DaisyUI tabs layout.
      *
+     * @param \Djot\Node\Block\Div $wrapper Original div node for attribute preservation.
      * @param list<\Djot\Node\Block\CodeBlock> $blocks Code blocks.
      */
-    protected function renderCodeGroup(array $blocks): string
+    protected function renderCodeGroup(Div $wrapper, array $blocks): string
     {
         $this->groupIndex++;
         $groupName = 'glaze-code-group-' . $this->groupIndex;
 
-        $html = '<div class="glaze-code-group" role="tablist">';
+        $attrs = $this->buildWrapperAttributes($wrapper);
+        $html = '<div' . $attrs . ' role="tablist">';
+
         foreach ($blocks as $index => $block) {
             $metadata = $this->parseLanguageMetadata($block->getLanguage(), $index + 1);
             $label = $this->escapeAttribute($metadata['label']);
@@ -123,9 +132,42 @@ protected function renderCodeGroup(array $blocks): string
         return $html . '</div>';
     }
 
+    /**
+     * Build wrapper div attributes, preserving custom attributes from the original div.
+     *
+     * @param \Djot\Node\Block\Div $wrapper Original div node.
+     */
+    protected function buildWrapperAttributes(Div $wrapper): string
+    {
+        $classes = ['glaze-code-group'];
+
+        // Add any additional classes from the original div (except 'code-group')
+        $existingClasses = (string)$wrapper->getAttribute('class');
+        foreach (preg_split('/\s+/', $existingClasses) ?: [] as $class) {
+            $class = trim($class);
+            if ($class !== '' && $class !== 'code-group' && !in_array($class, $classes, true)) {
+                $classes[] = $class;
+            }
+        }
+
+        $attrs = ' class="' . $this->escapeAttribute(implode(' ', $classes)) . '"';
+
+        // Copy other attributes (except class)
+        foreach ($wrapper->getAttributes() as $name => $value) {
+            if ($name === 'class') {
+                continue;
+            }
+            $attrs .= ' ' . $this->escapeAttribute($name) . '="' . $this->escapeAttribute((string)$value) . '"';
+        }
+
+        return $attrs;
+    }
+
     /**
      * Parse a Djot code fence language hint with optional `[label]` suffix.
      *
+     * Supports any non-whitespace characters in language names (c++, c#, text/html, etc.)
+     *
      * @param string|null $language Raw language hint from Djot code fence.
      * @param int $position One-based position in the group.
      * @return array{language: string|null, label: string}
@@ -137,16 +179,19 @@ protected function parseLanguageMetadata(?string $language, int $position): arra
             return ['language' => null, 'label' => 'Code ' . $position];
         }
 
-        $matches = [];
-        preg_match('/^(?<lang>[A-Za-z0-9_-]+)?(?:\s*\[(?<label>[^\]]+)\])?.*$/', $raw, $matches);
-
-        $resolvedLanguage = trim($matches['lang'] ?? '');
-        if ($resolvedLanguage === '') {
-            $resolvedLanguage = null;
+        // Match: optional language (any non-whitespace, non-[ chars), optional [label]
+        if (preg_match('/^(?:(?<lang>[^\s\[]+)\s*)?(?:\[(?<label>[^\]]+)])?$/', $raw, $matches) !== 1) {
+            return ['language' => $raw, 'label' => $raw];
         }
 
-        $resolvedLabel = trim($matches['label'] ?? '');
-        if ($resolvedLabel === '') {
+        $matchedLanguage = $matches['lang'] ?? null;
+        $matchedLabel = $matches['label'] ?? null;
+
+        $resolvedLanguage = $matchedLanguage !== '' ? $matchedLanguage : null;
+        $resolvedLabel = $matchedLabel !== null ? trim($matchedLabel) : null;
+
+        // Fallback label to language name or position
+        if ($resolvedLabel === null) {
             $resolvedLabel = $resolvedLanguage ?? 'Code ' . $position;
         }
 
diff --git a/tests/Unit/Render/Djot/CodeGroupExtensionTest.php b/tests/Unit/Render/Djot/CodeGroupExtensionTest.php
index a3593d6..8283701 100644
--- a/tests/Unit/Render/Djot/CodeGroupExtensionTest.php
+++ b/tests/Unit/Render/Djot/CodeGroupExtensionTest.php
@@ -70,4 +70,54 @@ public function testCodeGroupCanRenderWithoutPhiki(): void
         $this->assertStringContainsString('aria-label="php"', $html);
         $this->assertStringContainsString('aria-label="Code 2"', $html);
     }
+
+    /**
+     * Ensure special characters in language names are supported (c++, c#, text/html).
+     */
+    public function testSpecialCharactersInLanguageNames(): void
+    {
+        $converter = new DjotConverter();
+        $converter->addExtension(new CodeGroupExtension());
+
+        $html = $converter->convert(
+            "::: code-group\n\n```c++ [C++]\nint main() {}\n```\n\n```c# [C#]\nclass Program {}\n```\n\n:::\n",
+        );
+
+        $this->assertStringContainsString('aria-label="C++"', $html);
+        $this->assertStringContainsString('aria-label="C#"', $html);
+        $this->assertStringContainsString('class="language-c++"', $html);
+        $this->assertStringContainsString('class="language-c#"', $html);
+    }
+
+    /**
+     * Ensure custom attributes from the div are preserved.
+     */
+    public function testAttributePreservation(): void
+    {
+        $converter = new DjotConverter();
+        $converter->addExtension(new CodeGroupExtension());
+
+        $html = $converter->convert(
+            "{#my-code .custom-theme data-section=\"intro\"}\n::: code-group\n\n```php\ntest\n```\n\n:::\n",
+        );
+
+        $this->assertStringContainsString('id="my-code"', $html);
+        $this->assertStringContainsString('class="glaze-code-group custom-theme"', $html);
+        $this->assertStringContainsString('data-section="intro"', $html);
+    }
+
+    /**
+     * Ensure multiple custom classes are preserved alongside glaze-code-group.
+     */
+    public function testMultipleClassesPreserved(): void
+    {
+        $converter = new DjotConverter();
+        $converter->addExtension(new CodeGroupExtension());
+
+        $html = $converter->convert(
+            "{.extra-class .another-class}\n::: code-group\n\n```php\ntest\n```\n\n:::\n",
+        );
+
+        $this->assertStringContainsString('class="glaze-code-group extra-class another-class"', $html);
+    }
 }