Cleanup CSS for embed.

style.css

+/* Remove inherited style to embed GitLab Snippet */
+
+div.plugin_gitlabsnippet_gitlabsnippetsyntax pre {
+    border: unset;
+    box-shadow: unset;
+}
+
+div.plugin_gitlabsnippet_gitlabsnippetsyntax code {
+    background-color: unset;
+    box-shadow: unset;
+}
+

syntax/gitlabsnippetsyntax.php

@@ -99,7 +99,9 @@ class syntax_plugin_gitlabsnippet_gitlabsnippetsyntax extends DokuWiki_Syntax_Pl
 
         $snippetData = $data[0];
 
+        $renderer->doc .= '<div class="plugin_gitlabsnippet_gitlabsnippetsyntax">';
         $renderer->doc .= '<script src="' . $snippetData . '"></script>';
+        $renderer->doc .= '</div>';
 
         return true;
     }