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
@@ -531,7 +531,9 @@
 			$stylesheet_folder_url = dirname($stylesheet_file) . '/';
 
 			$url_params = Array ('events[fck]' => 'OnGetsEditorStyles', 'no_pass_through' => 1, 'pass' => 'm');
-			$styles_css = $this->Application->HREF('index', '_FRONT_END_', $url_params, 'index.php');
+
+			$prefix = $this->Application->isAdmin ? '_FRONT_END_' : '';
+			$styles_css = $this->Application->HREF('index', $prefix, $url_params, 'index.php');
 		}
 		else {
 			$stylesheet_folder_url = $this->Application->BaseURL(rtrim(EDITOR_PATH, '/'));