diff --git a/phpdotnet/phd/Package/PHP/ChunkedXHTML.php b/phpdotnet/phd/Package/PHP/ChunkedXHTML.php
index 1dc7bd7a..fad29242 100644
--- a/phpdotnet/phd/Package/PHP/ChunkedXHTML.php
+++ b/phpdotnet/phd/Package/PHP/ChunkedXHTML.php
@@ -8,11 +8,6 @@ public function __construct() {
         parent::__construct();
         $this->registerFormatName("PHP-Chunked-XHTML");
         $this->setExt(Config::ext() === null ? ".html" : Config::ext());
-
-        Config::setCss(array(
-            'http://www.php.net/styles/theme-base.css',
-            'http://www.php.net/styles/theme-medium.css',
-        ));
     }
 
     public function __destruct() {
diff --git a/phpdotnet/phd/Package/PHP/XHTML.php b/phpdotnet/phd/Package/PHP/XHTML.php
index 7c59b05b..384d4be3 100644
--- a/phpdotnet/phd/Package/PHP/XHTML.php
+++ b/phpdotnet/phd/Package/PHP/XHTML.php
@@ -190,6 +190,13 @@ public function __construct() {
         $this->mytextmap = array_merge(parent::getDefaultTextMap(), static::getDefaultTextMap());
         $this->dchunk = array_merge(parent::getDefaultChunkInfo(), static::getDefaultChunkInfo());
         $this->registerPIHandlers($this->pihandlers);
+
+        if (Config::css() === []) {
+            Config::setCss(array(
+                "http://www.php.net/styles/theme-base.css",
+                "http://www.php.net/styles/theme-medium.css",
+            ));
+        }
     }
 
     public function getDefaultElementMap() {