diff --git a/htdocs/langs/en_US/website.lang b/htdocs/langs/en_US/website.lang
index f01494fcdac..a05ead24df7 100644
--- a/htdocs/langs/en_US/website.lang
+++ b/htdocs/langs/en_US/website.lang
@@ -106,4 +106,5 @@ DeleteAlsoJs=Delete also all javascript files specific to this website?
 DeleteAlsoMedias=Delete also all medias files specific to this website?
 MyWebsitePages=My website pages
 SearchReplaceInto=Search | Replace into
-ReplaceString=New string
\ No newline at end of file
+ReplaceString=New string
+CSSContentTooltipHelp=Enter here CSS content. To avoid any conflict with the CSS of the application, be sure to prepend all declaration with the .bodywebsite class. For example:<br><br>#mycssselector, input.myclass:hover { ... }<br>must be<br>.bodywebsite #mycssselector, .bodywebsite input.myclass:hover { ... }<br><br>Note: If you have a large file without this prefix, you can use 'lessc' to convert it to append the .bodywebsite prefix everywhere.  
\ No newline at end of file
diff --git a/htdocs/website/index.php b/htdocs/website/index.php
index 04642d0dc84..3624843dba7 100644
--- a/htdocs/website/index.php
+++ b/htdocs/website/index.php
@@ -2557,7 +2557,8 @@ if ($action == 'editcss')
 
 	// CSS file
 	print '<tr><td class="tdtop">';
-	print $langs->trans('WEBSITE_CSS_INLINE');
+	$htmlhelp=$langs->trans("CSSContentTooltipHelp");
+	print $form->textwithpicto($langs->trans('WEBSITE_CSS_INLINE'), $htmlhelp, 1, 'help', '', 0, 2, 'csstooltip');
 	print '</td><td>';
 
 	$doleditor=new DolEditor('WEBSITE_CSS_INLINE', $csscontent, '', '220', 'ace', 'In', true, false, 'ace', 0, '100%', '');