Index: branches/5.3.x/core/units/helpers/fck_helper.php
===================================================================
--- branches/5.3.x/core/units/helpers/fck_helper.php
+++ branches/5.3.x/core/units/helpers/fck_helper.php
@@ -536,7 +536,7 @@
 			$styles_css = $this->Application->HREF('index', $prefix, $url_params, 'index.php');
 		}
 		else {
-			$stylesheet_folder_url = $this->Application->BaseURL(rtrim(EDITOR_PATH, '/'));
+			$stylesheet_folder_url = $this->Application->BaseURL() . trim(EDITOR_PATH, '/') . '/';
 			$styles_css = $stylesheet_folder_url . 'style.css';
 		}